Parameter explanations¶
Read what each parameter describes, its units and the models that use it. Applicability depends on the experiment and selected model. Compare names across interfaces.
Space group¶
The structure's space group.
Hermann-Mauguin symbol¶
The Hermann-Mauguin symbol of the space group.
Space-group setting¶
The setting of the space group, such as an origin choice or axes.
Space-group number¶
The number of the space group in International Tables, from 1 to 230.
Cell¶
The lengths and angles of the unit cell.
Cell length a¶
Length of the unit-cell edge along the a axis. Cell geometry determines calculated reflection positions; check the space-group symmetry before freeing cell dimensions.
Units: Å.
Cell length b¶
Length of the unit-cell edge along the b axis. Cell geometry determines calculated reflection positions; check the space-group symmetry before freeing cell dimensions.
Units: Å.
Cell length c¶
Length of the unit-cell edge along the c axis. Cell geometry determines calculated reflection positions; check the space-group symmetry before freeing cell dimensions.
Units: Å.
Cell angle α¶
Unit-cell angle between b and c (degrees; engine converts to radians).
Units: deg.
Cell angle β¶
Unit-cell angle between a and c (degrees; engine converts to radians).
Units: deg.
Cell angle γ¶
Unit-cell angle between a and b (degrees; engine converts to radians).
Units: deg.
Atom site¶
The atom sites of the structure: position, occupancy and isotropic displacement.
Atom-site identifier¶
Unique atom-site identifier.
Chemical element¶
Chemical symbol of the atom at this site.
Wyckoff position¶
Wyckoff letter of the site in its space group.
Displacement parameter type¶
Atomic displacement parameter type: Biso, Uiso, Bani, Uani or beta; Biso when absent.
| Option | Meaning |
|---|---|
| B iso | Isotropic, B in Ų. |
| U iso | Isotropic, U in Ų. |
| B aniso | Anisotropic, the B tensor in Ų. |
| U aniso | Anisotropic, the U tensor in Ų. |
| β | Anisotropic, the dimensionless β tensor. |
Fractional x-coordinate¶
Position of the representative atom site along the a lattice vector, expressed as a fraction of the unit cell rather than a Cartesian distance.
Units: dimensionless.
Fractional y-coordinate¶
Position of the representative atom site along the b lattice vector, expressed as a fraction of the unit cell rather than a Cartesian distance.
Units: dimensionless.
Fractional z-coordinate¶
Position of the representative atom site along the c lattice vector, expressed as a fraction of the unit cell rather than a Cartesian distance.
Units: dimensionless.
Occupancy¶
Site occupancy (raw occupancy; m/M multiplicity applied in |F|^2).
Units: dimensionless.
Isotropic or equivalent displacement¶
Isotropic atomic displacement parameter in the site's declared type: B for Biso, U for Uiso (B = 8 pi^2 U); an anisotropic site's equivalent isotropic value, derived.
Units: Ų.
| Form | Units |
|---|---|
Biso |
Ų |
Uiso |
Ų |
Bani |
Ų |
Uani |
Ų |
beta |
Ų |
Atomic displacement¶
The anisotropic displacement of each anisotropic atom site.
Anisotropic atom-site identifier¶
The id of the anisotropic atom site the row belongs to.
Displacement tensor component 11¶
Anisotropic displacement tensor component 11 (diagonal 11) in the site's declared type: U for Uani, B for Bani (Ų), dimensionless beta for beta.
Units: Ų for B/U; dimensionless for β.
| Form | Units |
|---|---|
Uani |
Ų |
Bani |
Ų |
beta |
dimensionless |
Displacement tensor component 22¶
Anisotropic displacement tensor component 22 (diagonal 22) in the site's declared type: U for Uani, B for Bani (Ų), dimensionless beta for beta.
Units: Ų for B/U; dimensionless for β.
| Form | Units |
|---|---|
Uani |
Ų |
Bani |
Ų |
beta |
dimensionless |
Displacement tensor component 33¶
Anisotropic displacement tensor component 33 (diagonal 33) in the site's declared type: U for Uani, B for Bani (Ų), dimensionless beta for beta.
Units: Ų for B/U; dimensionless for β.
| Form | Units |
|---|---|
Uani |
Ų |
Bani |
Ų |
beta |
dimensionless |
Displacement tensor component 12¶
Anisotropic displacement tensor component 12 (off-diagonal 12) in the site's declared type: U for Uani, B for Bani (Ų), dimensionless beta for beta.
Units: Ų for B/U; dimensionless for β.
| Form | Units |
|---|---|
Uani |
Ų |
Bani |
Ų |
beta |
dimensionless |
Displacement tensor component 13¶
Anisotropic displacement tensor component 13 (off-diagonal 13) in the site's declared type: U for Uani, B for Bani (Ų), dimensionless beta for beta.
Units: Ų for B/U; dimensionless for β.
| Form | Units |
|---|---|
Uani |
Ų |
Bani |
Ų |
beta |
dimensionless |
Displacement tensor component 23¶
Anisotropic displacement tensor component 23 (off-diagonal 23) in the site's declared type: U for Uani, B for Bani (Ų), dimensionless beta for beta.
Units: Ų for B/U; dimensionless for β.
| Form | Units |
|---|---|
Uani |
Ų |
Bani |
Ų |
beta |
dimensionless |
Scattering length¶
Neutron coherent scattering lengths that replace the built-in table for an element or isotope.
Type¶
The element or isotope the scattering length applies to.
Neutron scattering length¶
The coherent neutron scattering length.
Units: fm.
Bond settings¶
How bonds between atoms are found.
Minimum bond distance¶
Atoms closer than this are not bonded.
Units: Å.
Bond-distance tolerance¶
How much longer than the sum of the covalent radii a bond may be.
Units: Å.
Appearance¶
How the structure view draws the structure: atoms, colours, labels and what else it shows.
Atom radius model¶
What sets the size of each atom.
| Option | Meaning |
|---|---|
| Covalent radius | The covalent radius. |
| Van der Waals radius | The van der Waals radius. |
| Ionic radius | The ionic radius. |
| Displacement | The atomic displacement, at the probability set. |
Colours¶
The colours the atoms take, by element.
| Option | Meaning |
|---|---|
| Jmol | The Jmol colours. |
| VESTA | The VESTA colours. |
Atom scale¶
The atoms' drawn size as a share of their radius.
Ellipsoid probability¶
The probability the displacement ellipsoids enclose.
Labels¶
Whether each atom is labelled.
Atoms shown¶
Which atoms are drawn.
| Option | Meaning |
|---|---|
| All | Every atom in the cell. |
| Asymmetric unit | The atoms of the asymmetric unit. |
| None | No atoms. |
Bonds¶
Whether bonds are drawn.
Cell¶
Whether the unit cell is drawn.
Axes¶
Whether the cell axes are drawn.
Symmetry operator¶
The space group's symmetry operators, in the order a symmetry code refers to them.
Symmetry operation¶
A symmetry operator as x, y, z expressions.
Atom in the cell¶
Every atom of the unit cell, generated from the atom sites by symmetry.
Source atom site¶
The atom site this atom is generated from.
Generating symmetry operation¶
The symmetry code that generates this atom from its site.
Fractional x-coordinate¶
Position of the symmetry-generated atom along the a lattice vector, expressed as a fraction of the unit cell rather than a Cartesian distance.
Fractional y-coordinate¶
Position of the symmetry-generated atom along the b lattice vector, expressed as a fraction of the unit cell rather than a Cartesian distance.
Fractional z-coordinate¶
Position of the symmetry-generated atom along the c lattice vector, expressed as a fraction of the unit cell rather than a Cartesian distance.
Cartesian x-coordinate¶
Cartesian X-coordinate.
Units: Å.
Cartesian y-coordinate¶
Cartesian Y-coordinate.
Units: Å.
Cartesian z-coordinate¶
Cartesian Z-coordinate.
Units: Å.
Occupancy¶
Occupancy of the atom.
Isotropic displacement U¶
Isotropic displacement of the atom, as U.
Units: Ų.
Coincident-atom cluster¶
Atoms within one shared position carry the same cluster number.
Bond¶
The bonds between the atoms of the cell.
Atom 1¶
The first atom of the bond, in the atoms of the cell.
Atom 2¶
The second atom of the bond, in the atoms of the cell.
Site 1¶
The atom site of the first atom.
Site 2¶
The atom site of the second atom.
Symmetry 1¶
The symmetry code of the first atom.
Symmetry 2¶
The symmetry code of the second atom.
Distance¶
The length of the bond.
Units: Å.
Cartesian frame¶
The matrix from fractional to Cartesian coordinates.
Coordinate-transform element 11¶
Element 11 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 12¶
Element 12 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 13¶
Element 13 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 21¶
Element 21 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 22¶
Element 22 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 23¶
Element 23 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 31¶
Element 31 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 32¶
Element 32 of the fractional-to-Cartesian matrix.
Units: Å.
Coordinate-transform element 33¶
Element 33 of the fractional-to-Cartesian matrix.
Units: Å.
Axes¶
How the Cartesian axes are placed in the cell.
Experiment type¶
What kind of experiment this is: sample form, beam mode, probe and scattering type.
Beam mode¶
How the pattern is measured.
| Option | Meaning |
|---|---|
| Constant wavelength | One wavelength, the pattern measured against the scattering angle 2θ. |
| Time-of-flight | A white beam, the pattern measured against the time of flight. |
Sample form¶
The form of the sample.
| Option | Meaning |
|---|---|
| Powder | A polycrystalline sample. |
| Single crystal | One crystal. |
Probe¶
The radiation scattered by the sample.
| Option | Meaning |
|---|---|
| Neutron | Neutrons, scattered by the nuclei. |
| X-ray | X-rays, scattered by the electrons. |
Scattering type¶
Which scattering the pattern is modelled with.
| Option | Meaning |
|---|---|
| Bragg | Bragg peaks from the average structure. |
| Total | Bragg and diffuse scattering together. |
Dimensionality¶
The dimensionality of the measured pattern.
| Option | Meaning |
|---|---|
| 1D | A one-dimensional pattern. |
Polarisation¶
The polarisation of the incident beam; an X-ray experiment states the inapplicable value.
| Option | Meaning |
|---|---|
| Unpolarised | An unpolarised neutron beam. |
| Not applicable | An X-ray experiment, whose beam polarisation is not a setting here. |
Calculation range¶
The grid a pattern is calculated on when no data are measured.
Min¶
The first 2θ of the calculation grid.
Units: deg.
Max¶
The last 2θ of the calculation grid.
Units: deg.
Step¶
The 2θ step of the calculation grid.
Units: deg.
Scattering angle¶
The 2θ points of the calculation grid.
Units: deg.
Min¶
The first time of flight of the calculation grid.
Units: µs.
Max¶
The last time of flight of the calculation grid.
Units: µs.
Step¶
The time-of-flight step of the calculation grid.
Units: µs.
Time of flight¶
The time-of-flight points of the calculation grid.
Units: µs.
Background¶
The background under the diffraction peaks.
Background anchor intensity¶
Line-segment background intensity anchor (dimensionless in the reduced pattern; linear).
Units: intensity units of the pattern.
Background anchor position¶
Background anchor position (TOF, us); a fixed node, not a refinable Parameter.
Units: µs.
Background coefficient¶
Polynomial or Chebyshev background coefficient of the row's order (dimensionless in the reduced pattern; linear).
Units: intensity units of the pattern.
Background term order¶
Order m of a polynomial or Chebyshev background term (a non-negative integer; a fixed node, not a refinable Parameter).
Units: dimensionless.
Polynomial background origin¶
Origin of the polynomial background, FullProf Bkpos: the terms are powers of x/origin - 1 (in the pattern's axis units; non-zero).
Units: native pattern-axis units (degrees 2θ or µs).
Chebyshev domain minimum¶
Lower end of the Chebyshev background's normalisation domain (in the pattern's axis units).
Units: native pattern-axis units (degrees 2θ or µs).
Chebyshev domain maximum¶
Upper end of the Chebyshev background's normalisation domain (in the pattern's axis units; above x_min).
Units: native pattern-axis units (degrees 2θ or µs).
Background model¶
The background function.
| Option | Meaning |
|---|---|
| Line segment | Straight lines between background points. |
| Chebyshev | A sum of Chebyshev polynomials. |
| Polynomial | A polynomial in the scattering variable. |
Background row identifier¶
The name of a background point or term.
Background estimation¶
How the background is estimated from the measured pattern.
Estimation mode¶
Whether the background is edited by hand or estimated again on every change.
| Option | Meaning |
|---|---|
| Manual | The background is edited by hand; Estimate replaces it when asked. |
| Auto | The background is estimated again whenever the data or the settings change. |
Method¶
The background estimation method.
| Option | Meaning |
|---|---|
| Auto | The default method, arPLS. |
| SNIP | SNIP (Ryan et al. 1988): clips the peaks away. |
| arPLS | arPLS (Baek et al. 2015): asymmetrically reweighted penalized least squares. |
| FABC | FABC (Cobas et al. 2006): finds the baseline points by a wavelet transform. |
Peak width¶
The peak width the estimation assumes, in points.
Smoothness¶
How smooth the estimated background is.
Number of background anchors¶
How many background points the estimation keeps.
Background thinning tolerance¶
How far, in units of the noise, the thinned background may stray.
Anchors within peaks¶
What happens to a background point that falls in a peak.
| Option | Meaning |
|---|---|
| Move | Move it to the nearest allowed point. |
| Drop | Drop it. |
Calculated-peak treatment¶
What the estimation does with the peaks of the calculated pattern.
| Option | Meaning |
|---|---|
| Auto | Subtract them when the calculated pattern matches the data. |
| Subtract | Always subtract them when there is a calculated pattern. |
| Ignore | Never subtract them. |
Max terms¶
The most terms a Chebyshev or polynomial background may take.
Inputs digest¶
A checksum of what the last estimate was made from.
Points digest¶
A checksum of the background the last estimate wrote.
Instrument¶
The instrument setup and calibration.
TOF offset¶
TOF calibration zero offset (TOF = zero + Dtt1d + Dtt2d^2 + recip/d).
Units: µs.
TOF linear¶
TOF calibration linear coefficient Dtt1 (us/A).
Units: µs/Å.
TOF quadratic¶
TOF calibration quadratic coefficient Dtt2 (us/A^2).
Units: µs/Ų.
TOF reciprocal¶
TOF calibration reciprocal (1/d) coefficient (us*A); round-tripped, held fixed in the free set.
Units: µs·Å.
Read and saved, but not used in the calculation.
Zero-point angular offset¶
CW zero-point offset in degrees 2theta, subtracted from the observed axis.
Units: deg.
Wavelength¶
Incident neutron wavelength in angstroms (single wavelength; the doublet tags are X-ray scope).
Units: Å.
| Form | Units |
|---|---|
doublet |
Å |
Sample displacement¶
CW sample-displacement line shift in degrees 2theta (FullProf SyCos): adds displacement*cos(2theta_B) to each reflection's position.
Units: deg.
Sample transparency¶
CW sample-transparency line shift in degrees 2theta (FullProf SySin): adds transparency*sin(2theta_B) to each reflection's position.
Units: deg.
Polarization coefficient¶
X-ray CW polarization coefficient K (FullProf Rpolarz): the intensity carries P = 1 - K + K cos^2(2theta_m) cos^2(2theta); 0 disables the correction.
Units: dimensionless.
Monochromator 2θ¶
X-ray CW pre-specimen monochromator angle 2theta_m in degrees (FullProf stores Cthm = cos^2(2theta_m)); 0 means no monochromator.
Units: deg.
Secondary wavelength¶
X-ray CW second incident wavelength in angstroms (FullProf Lambda2, e.g. Cu K-alpha2); used when setup_wavelength_2_to_1_ratio is not 0.
Units: Å.
Secondary-to-primary intensity ratio¶
X-ray CW intensity of the second wavelength relative to the first (FullProf Ratio); 0 means a single wavelength.
Units: dimensionless.
Instrument¶
The instrument the pattern was measured on, or unknown.
Facility¶
The facility the instrument belongs to, or unknown.
2θ bank¶
The scattering angle of the time-of-flight detector bank.
Units: deg.
Peak profile¶
The shape and width of the diffraction peaks.
Exponential rise coefficient α₀¶
Back-to-back exponential rise-rate coefficient alpha_0 (rate, 1/us; no closed unit code).
Units: µs⁻¹.
Exponential rise coefficient α₁¶
Back-to-back exponential rise-rate coefficient alpha_1 (alpha(d)=alpha_0+alpha_1/d).
Units: Å/µs.
Exponential decay coefficient β₀¶
Back-to-back exponential decay-rate coefficient beta_0 (rate, 1/us; no closed unit code).
Units: µs⁻¹.
Exponential decay coefficient β₁¶
Back-to-back exponential decay-rate coefficient beta_1 (beta(d)=beta_0+beta_1/d^4).
Units: Å⁴/µs.
Gaussian broadening σ₀²¶
Gaussian VARIANCE coefficient sigma_0^2 (variance domain; TCH consumes FWHM_G=sqrt(sigma^2)*sqrt(8 ln 2)).
Units: µs².
Gaussian broadening σ₁²¶
Gaussian VARIANCE coefficient sigma_1^2 (d^2 term; variance domain).
Units: µs²/Ų.
Gaussian broadening σ₂²¶
Gaussian VARIANCE coefficient sigma_2^2 (d^4 term; us^2/A^4 not in closed vocab -> none).
Units: µs²/Å⁴.
Gaussian broadening size G¶
Gaussian isotropic size broadening (variance contribution).
Units: µs²/Å⁴.
Gaussian broadening strain G¶
Gaussian isotropic strain broadening (variance contribution).
Units: µs²/Ų.
Lorentzian broadening γ₀¶
Lorentzian FWHM coefficient gamma_0 (FWHM domain, H_L; consumed as FWHM directly, no sqrt(8 ln 2)).
Units: µs.
Lorentzian broadening γ₁¶
Lorentzian FWHM coefficient gamma_1 (d term; FWHM domain).
Units: µs/Å.
Lorentzian broadening γ₂¶
Lorentzian FWHM coefficient gamma_2 (d^2 term; FWHM domain).
Units: µs/Ų.
Lorentzian broadening size L¶
Lorentzian isotropic size broadening (FWHM).
Units: µs/Ų.
Lorentzian broadening strain L¶
Lorentzian isotropic strain broadening (FWHM).
Units: µs/Å.
Gaussian broadening U¶
Caglioti Gaussian FWHM coefficient U (tan^2(theta) term; H_G^2 in deg^2).
Units: deg².
Gaussian broadening V¶
Caglioti Gaussian FWHM coefficient V (tan(theta) term; H_G^2 in deg^2).
Units: deg².
Gaussian broadening W¶
Caglioti Gaussian FWHM coefficient W (constant term; H_G^2 in deg^2).
Units: deg².
Lorentzian broadening X¶
Lorentzian FWHM coefficient X, strain-like (tan(theta) term; H_L in deg).
Units: deg.
Lorentzian broadening Y¶
Lorentzian FWHM coefficient Y, size-like (1/cos(theta) term; H_L in deg).
Units: deg.
Pseudo-Voigt mixing intercept¶
Pseudo-Voigt mixing at 2theta = 0: eta = eta_0 + eta_1 2theta (FullProf Eta0).
Units: dimensionless.
Pseudo-Voigt mixing slope¶
Pseudo-Voigt mixing slope per degree 2theta: eta = eta_0 + eta_1 2theta (FullProf X of Npr 5).
Units: 1/deg.
FCJ asymmetry S/L¶
Finger-Cox-Jephcoat asymmetry parameter 1: S/L, half the sample height over the diffractometer radius.
Units: dimensionless.
FCJ asymmetry D/L¶
Finger-Cox-Jephcoat asymmetry parameter 2: D/L, half the detector height over the diffractometer radius.
Units: dimensionless.
Bérar-Baldinozzi asymmetry A₀¶
Berar-Baldinozzi asymmetry coefficient A0 (Fa/tan theta).
Units: dimensionless.
Bérar-Baldinozzi asymmetry B₀¶
Berar-Baldinozzi asymmetry coefficient B0 (Fb/tan theta).
Units: dimensionless.
Bérar-Baldinozzi asymmetry A₁¶
Berar-Baldinozzi asymmetry coefficient A1 (Fa/tan 2theta).
Units: dimensionless.
Bérar-Baldinozzi asymmetry B₁¶
Berar-Baldinozzi asymmetry coefficient B1 (Fb/tan 2theta).
Units: dimensionless.
Bérar-Baldinozzi asymmetry AsyLim¶
Berar-Baldinozzi limit angle (deg 2theta): reflections at or above it get no asymmetry correction (FullProf AsyLim); default 180.
Units: deg.
Profile¶
The peak-profile function.
| Option | Meaning |
|---|---|
| Gaussian | A Gaussian peak with the Caglioti width. |
| Lorentzian | A Lorentzian peak. |
| Pseudo-Voigt | A pseudo-Voigt peak with a refinable mixing. |
| Pseudo-Voigt + Bérar-Baldinozzi asymmetry | A pseudo-Voigt peak with the Bérar-Baldinozzi asymmetry correction. |
| Thompson-Cox-Hastings pseudo-Voigt (TCH) | The Thompson-Cox-Hastings pseudo-Voigt peak. |
| Thompson-Cox-Hastings pseudo-Voigt (TCH) + Finger-Cox-Jephcoat asymmetry (FCJ) | The TCH peak with the Finger-Cox-Jephcoat axial-divergence asymmetry. |
| Jorgensen | The back-to-back exponentials convolved with a Gaussian. |
| Jorgensen-Von Dreele | The back-to-back exponentials convolved with a pseudo-Voigt. |
| Pseudo-Voigt | A time-of-flight pseudo-Voigt peak. |
Peak calculation cutoff¶
How far from its centre a peak is calculated, in units of its width.
Excluded region¶
Ranges of the pattern left out of the fit.
Id¶
The name of the excluded region.
Start¶
Where the excluded region starts.
Units: deg.
| Form | Units |
|---|---|
constant wavelength |
deg |
time-of-flight |
µs |
End¶
Where the excluded region ends.
Units: deg.
| Form | Units |
|---|---|
constant wavelength |
deg |
time-of-flight |
µs |
Extinction¶
A single crystal's extinction correction: its type, mosaic distribution and parameters.
Domain radius¶
Becker-Coppens domain (mosaic block) radius r (micrometres; extinction types II and mixed; single crystal; a fit parameter).
Units: μm.
Mosaic spread¶
Becker-Coppens mosaic spread g of the crystal, the inverse width of its mosaic distribution (larger is narrower; radians to the minus one; extinction types I and mixed; single crystal; a fit parameter).
Units: rad⁻¹.
Crystal radius¶
Radius of the crystal taken as a sphere, which sets each reflection's mean path length through it for the Becker-Coppens secondary extinction (millimetres, as _exptl_crystal.size_rad; every Becker-Coppens type; single crystal; a descriptor, never fitted).
Units: mm.
Extinction coefficient¶
Larson's empirical extinction coefficient x, as SHELXL's EXTI: F2calc is multiplied by [1 + 0.001 x F2calc lambda^3 / sin 2theta]^(-1/2) (extinction type larson-isotropic; single crystal; a fit parameter).
Units: dimensionless.
X11¶
The term of h² in Larson's anisotropic extinction tensor x_aniso = x11 h^2 + x22 k^2 + x33 l^2 + x12 hk + x13 hl + x23 kl, which takes the place of 4 x (sin theta/lambda)^2 (FullProf's Ext1; extinction type larson-anisotropic; single crystal; a fit parameter).
Units: dimensionless.
X22¶
The term of k² in Larson's anisotropic extinction tensor x_aniso = x11 h^2 + x22 k^2 + x33 l^2 + x12 hk + x13 hl + x23 kl, which takes the place of 4 x (sin theta/lambda)^2 (FullProf's Ext2; extinction type larson-anisotropic; single crystal; a fit parameter).
Units: dimensionless.
X33¶
The term of l² in Larson's anisotropic extinction tensor x_aniso = x11 h^2 + x22 k^2 + x33 l^2 + x12 hk + x13 hl + x23 kl, which takes the place of 4 x (sin theta/lambda)^2 (FullProf's Ext3; extinction type larson-anisotropic; single crystal; a fit parameter).
Units: dimensionless.
X12¶
The term of hk in Larson's anisotropic extinction tensor x_aniso = x11 h^2 + x22 k^2 + x33 l^2 + x12 hk + x13 hl + x23 kl, which takes the place of 4 x (sin theta/lambda)^2 (FullProf's Ext4; extinction type larson-anisotropic; single crystal; a fit parameter).
Units: dimensionless.
X13¶
The term of hl in Larson's anisotropic extinction tensor x_aniso = x11 h^2 + x22 k^2 + x33 l^2 + x12 hk + x13 hl + x23 kl, which takes the place of 4 x (sin theta/lambda)^2 (FullProf's Ext5; extinction type larson-anisotropic; single crystal; a fit parameter).
Units: dimensionless.
X23¶
The term of kl in Larson's anisotropic extinction tensor x_aniso = x11 h^2 + x22 k^2 + x33 l^2 + x12 hk + x13 hl + x23 kl, which takes the place of 4 x (sin theta/lambda)^2 (FullProf's Ext6; extinction type larson-anisotropic; single crystal; a fit parameter).
Units: dimensionless.
Type¶
The extinction correction of a single crystal.
| Option | Meaning |
|---|---|
| None | No extinction correction. |
| Isotropic Becker-Coppens type I | Becker-Coppens secondary extinction set by the mosaic spread. |
| Isotropic Becker-Coppens type II | Becker-Coppens secondary extinction set by the domain radius. |
| Isotropic Becker-Coppens mixed | Becker-Coppens secondary extinction set by both the mosaic spread and the domain radius. |
| Isotropic Larson | Larson's empirical coefficient, as SHELXL's EXTI. |
| Anisotropic Larson | Larson's anisotropic extinction tensor. |
Mosaic distribution¶
The shape of a Becker-Coppens crystal's mosaic distribution.
| Option | Meaning |
|---|---|
| Gaussian | A Gaussian mosaic distribution. |
| Lorentzian | A Lorentzian mosaic distribution. |
Linked structure¶
The structures that contribute to the pattern, each with its scale.
Scale¶
Scale factor of one linked structure's (phase's) pattern, the overall pattern scale when there is one structure (dimensionless; linear).
Units: dimensionless.
Structure¶
The structure that contributes to the pattern.
Enabled¶
Whether the structure contributes to the pattern.
Phase mass fraction¶
The structure's weight fraction in the sample, from the scales (Hill and Howard); computed, never edited.
Absorption¶
The absorption correction.
ABSCOR1¶
TOF sample absorption coefficient ABSCOR1 (muR = ABSCOR1 * lambda; refinable).
Units: Å⁻¹.
ABSCOR2¶
TOF sample absorption lambda-power ABSCOR2 (round-tripped, held fixed; freeing it is a hard error).
Read and saved, but not yet used in the calculation (planned).
ΜR¶
CW cylinder sample absorption mu*R (mu the linear absorption coefficient, R the cylinder RADIUS; evaluated at each reflection's Bragg theta; refinable).
Units: dimensionless.
Type¶
The absorption correction.
| Option | Meaning |
|---|---|
| None | No absorption correction. |
| Cylinder (Hewat) | The Hewat (1979) polynomial for a cylindrical sample. |
| Cylinder (Lobanov) | The Lobanov and Alte da Veiga (1998) fit for a cylindrical sample. |
Preferred orientation¶
The March-Dollase preferred-orientation correction per structure.
March-Dollase coefficient¶
March-Dollase coefficient r (FullProf Pref1, IUCr _pd_pref_orient_March_Dollase.r; 1 = no texture, <1 platy, >1 needle; must be > 0; a fit parameter).
Units: dimensionless.
Randomly oriented fraction¶
Random (untextured) fraction mixed with the March-Dollase term (FullProf Pref2; a fit parameter).
Units: dimensionless.
Structure¶
The structure the correction applies to.
Miller index h¶
The h index of the preferred-orientation direction.
Miller index k¶
The k index of the preferred-orientation direction.
Miller index l¶
The l index of the preferred-orientation direction.
Observed reflections¶
Which of a single crystal's reflections count as observed, for its counts and R factors.
Observed-reflection threshold¶
The multiple n of its su above which a single crystal's reflection counts as observed; 2 when absent.
On¶
Whether the observed threshold is on the intensity or the amplitude; the intensity when absent.
| Option | Meaning |
|---|---|
| I | The intensity: I > n u(I). |
| F | The amplitude: F > n u(F). |
Threshold¶
The observed threshold as CIF writes it, such as I>2u(I); a save writes it beside the counts and R factors it gives.
Scattering source¶
The published tables the scattering factors and lengths come from.
X-ray form factors¶
The published table the X-ray atomic form factors come from.
| Option | Meaning |
|---|---|
| Waasmaier & Kirfel (1995) | Waasmaier and Kirfel, Acta Cryst. A51 (1995) 416. |
| International Tables C (1992) | International Tables for Crystallography, Vol. C (1992). |
X-ray dispersion¶
The published table the anomalous dispersion corrections come from.
| Option | Meaning |
|---|---|
| Cromer & Liberman | Cromer and Liberman, calculated for the wavelength. |
| Sasaki (1989) | Sasaki, KEK Report 88-14 (1989). |
| International Tables C (1992) | International Tables for Crystallography, Vol. C (1992). |
| None | No anomalous dispersion correction. |
Neutron scattering lengths¶
The published table the neutron scattering lengths come from.
| Option | Meaning |
|---|---|
| Rauch & Waschkowski (2003) | Rauch and Waschkowski (2003), extended with the isotopes it lacks. |
| Sears (1992) | Sears, Neutron News 3 (1992) 26. |
Data source¶
The file the measured data were read from.
Measured-data filename¶
The file the measured data were read from.
Measured data point¶
The measured pattern and the values calculated at each of its points.
Scattering angle¶
The scattering angle of each point.
Units: deg.
Time of flight¶
The time of flight of each point.
Units: µs.
Measured intensity¶
The measured intensity.
Measured intensity uncertainty¶
The standard uncertainty of the measured intensity.
Interplanar spacing¶
The d-spacing of each point.
Units: Å.
Calculated intensity¶
The calculated intensity, the background included.
Background intensity¶
The background at each point.
Calculation status¶
Whether the point takes part in the calculation and the fit.
| Option | Meaning |
|---|---|
| Included | The point is calculated and fitted. |
| Excluded | The point lies in an excluded region and is not calculated. |
Calculated point¶
The calculated pattern the command line writes.
Point¶
The index of the point in the calculated pattern.
Structure curves¶
The structures the per-point curves follow.
Structure order¶
The structures whose curves the per-point lists hold, in their order.
Structure curve¶
Each structure's calculated curve, one value per structure at every point of the pattern.
Structure calc¶
Each structure's calculated intensity at the point, the background excluded, in the order _pd_calc_overall.component_presentation_order gives.
Reflection¶
The Bragg reflections of each linked structure.
Structure¶
The structure the reflection belongs to.
Interplanar spacing¶
The d-spacing of the reflection.
Units: Å.
Sin θ/λ¶
sin θ over λ of the reflection.
Units: 1/Å.
Miller index h¶
The h index of the reflection.
Miller index k¶
The k index of the reflection.
Miller index l¶
The l index of the reflection.
F calc¶
The calculated structure-factor amplitude.
F meas¶
The measured structure-factor amplitude, the square root of a single crystal's measured F², as its chart plots it in F.
F² calc¶
The calculated squared structure factor.
Measured intensity¶
The measured squared structure factor of a single crystal's reflection.
Measured intensity uncertainty¶
The standard uncertainty of the measured squared structure factor.
Calculated intensity¶
The calculated squared structure factor of a single crystal's reflection.
Λ¶
The wavelength a time-of-flight single crystal's reflection was measured at.
Units: Å.
Scattering angle¶
The Bragg angle of the reflection.
Units: deg.
Time of flight¶
The time of flight of the reflection.
Units: µs.
Project¶
The project's name, title, description and authors.
Name¶
The project's short name, which names its folder.
Title¶
The project's title.
Description¶
What the project is about.
Authors¶
The people the project and its report credit, separated by semicolons.
Location¶
The project's folder.
Created¶
When the project was created.
Last modified¶
When the project was last saved.
Timestamp¶
A machine-readable time of the last save.
Standard uncertainties¶
How values with a standard uncertainty are written and shown.
Uncertainty rounding rule¶
How a value with a standard uncertainty is rounded when it is written and shown.
| Option | Meaning |
|---|---|
| IUCr recommendation: 1 digit, or 2 from 10 to 19 | The IUCr recommendation 12: one significant digit in the uncertainty, two from 10 to 19. |
| Always 2 digits, 10 to 99 | Always two significant digits in the uncertainty, the practice the IUCr also admits. |
Report¶
Which report formats are saved, and what they leave out.
HTML¶
Whether Save report writes the HTML report.
PDF¶
Whether Save report writes the PDF report.
CIF¶
Whether Save report writes the CIF report.
Embed chart libraries¶
Whether the HTML report carries its chart libraries, so it opens offline.
Excluded¶
The report sections left out.
Correlation chart¶
Settings of the parameter-correlation chart.
Threshold¶
The smallest absolute correlation the chart shows.
Pattern chart¶
Settings of the diffraction pattern chart.
X-axis¶
The pattern chart's horizontal axis.
| Option | Meaning |
|---|---|
| Measured axis | The experiment's own axis: 2θ or time of flight. |
| d-spacing | The d-spacing of each point. |
Calculator¶
The calculation engine an experiment names.
Calculator¶
The calculation engine.
| Option | Meaning |
|---|---|
| crysta | The crysta engine. |
Minimizer¶
The minimizer and its settings.
Minimizer¶
The minimizer.
| Option | Meaning |
|---|---|
| crysta | crysta's own least-squares minimizer. |
Max iterations¶
The most iterations a fit may take.
Descent¶
The descent strategy of the minimizer.
| Option | Meaning |
|---|---|
| Ladder | The default descent. |
| Fast descent | A faster descent that takes fewer steps. |
| Fast descent with linear snap | The fast descent, solving the linear parameters exactly at each step. |
| Fast descent with guarded linear snap | The fast descent, keeping a linear snap only when it lowers χ². |
| Multi-start with pruning | Several starts, the worse ones dropped as the fit goes on. |
Tolerance¶
The relative change of χ² at which a fit stops.
Fitting mode¶
How the experiments of a project are fitted.
Fitting mode¶
How the experiments of the project are fitted.
| Option | Meaning |
|---|---|
| Single experiment | The one experiment is fitted on its own. |
| Joint: all experiments at once | All experiments are fitted together. |
| Sequential: each from the previous | Each data file is fitted, starting from the previous result. |
| Independent: each from the same start | Each data file is fitted from the same start. |
Fitted reflections¶
Which of a single crystal's reflections a fit uses.
Fitted-reflection threshold¶
The multiple n of its su above which a single crystal's reflection is fitted; every reflection when absent.
Alias¶
Short names for parameters, used in constraints.
Alias¶
The short name.
Parameter¶
The parameter the short name stands for.
Constraint¶
Expressions that compute a parameter from others.
Id¶
The name of the constraint.
Expression¶
The expression, such as occ_Ba = 1 - occ_La.
Enabled¶
Whether the constraint applies.
Joint-fit weights¶
Each experiment's weight in a joint fit.
Weight¶
The experiment's weight in a joint fit.
Sequential fit¶
Which data files a sequential fit runs over.
Data directory¶
The folder of the data files.
Files¶
Which files of the folder are fitted.
Reverse¶
Whether the files are fitted in reverse order.
Template¶
The experiment every file is fitted with.
Scan extraction rule¶
Rules that read a value, such as a temperature, from each data file name.
Id¶
The name of the value read from each file name.
Extracted value name¶
What the value is stored as.
Pattern¶
The pattern that finds the value in the file name.
Required¶
Whether a file whose name does not match fails.
File header¶
The header every .edi file starts with.
Schema version¶
The version of the .edi format the file follows.
Saved report¶
The report files saved from this project.
Format¶
The format of a saved report file.
| Option | Meaning |
|---|---|
| HTML | An HTML page with interactive charts. |
| A PDF document on A4 pages. | |
| CIF | A CIF file with the official CIF names. |
File¶
The saved report file, in the reports folder.
Saved¶
When the report file was saved.
Project saved¶
When the project was last saved before the report was.
Digest¶
A checksum of the saved report file.
Fit start value¶
The values the last fit started from, kept so the fit can be undone.
Parameter¶
The parameter the start value belongs to.
Start value¶
The value the last fit started from.
Start error¶
The uncertainty the parameter had when the last fit started.
Start tied¶
Whether the parameter was tied when the last fit started.
Fit result¶
The outcome of the last fit.
Kind¶
What kind of fit gave the result.
Success¶
Whether the fit converged.
Message¶
The minimizer's message.
Iterations¶
How many iterations the fit took.
Time¶
How long the fit took.
Units: s.
Reduced χ²¶
χ² divided by the degrees of freedom.
Objective¶
The quantity the fit minimized.
Objective value¶
The value of the objective at the end of the fit.
Number of fitted observations¶
How many data points the fit used.
Parameters¶
How many parameters the project has.
Free parameters¶
How many parameters the fit refined.
Degrees of freedom¶
The points minus the free parameters.
Covariance¶
Whether the fit gave a covariance matrix.
Exit reason¶
Why the fit stopped.
Rwp¶
The weighted profile R factor.
Units: %.
| Form | Units |
|---|---|
single crystal |
% |
Rp¶
The profile R factor.
Units: %.
| Form | Units |
|---|---|
single crystal |
% |
Rexp¶
The expected weighted profile R factor.
Units: %.
CRp¶
The background-corrected profile R factor.
Units: %.
CRwp¶
The background-corrected weighted profile R factor.
Units: %.
Profile¶
The peak profile the fit used.
Background¶
The background the fit used.
Descent¶
The descent strategy the fit used.
Experiment fit result¶
The agreement factors of each experiment in the last fit.
Number of fitted observations¶
How many data points of the experiment the fit used.
Rp¶
The experiment's profile R factor.
Units: %.
| Form | Units |
|---|---|
single crystal |
% |
Rwp¶
The experiment's weighted profile R factor.
Units: %.
| Form | Units |
|---|---|
single crystal |
% |
Rexp¶
The experiment's expected weighted profile R factor.
Units: %.
CRp¶
The experiment's background-corrected profile R factor.
Units: %.
CRwp¶
The experiment's background-corrected weighted profile R factor.
Units: %.
Reduced χ²¶
The experiment's reduced χ².
Structure fit result¶
The agreement factors of each structure in each experiment.
R Bragg¶
The structure's Bragg R factor in the experiment.
Units: %.
R F¶
The structure's structure-factor R factor in the experiment.
Units: %.
Correlation¶
The correlations between the fitted parameters.
Id¶
The name of the correlation.
Source¶
What kind of fit the correlation comes from.
Parameter 1¶
The first parameter.
Parameter 2¶
The second parameter.
Correlation¶
The correlation coefficient between the two parameters.
File¶
The data file of a sequential fit the correlation belongs to.
Report block¶
The name each data block of the CIF report gives itself.
Block¶
The name of a data block of the CIF report, which a phase link refers to.