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====== p ======
**[//peak_typ//****//e//** **$type]**
Sets the peak type for a phase. The following //peak_type//’s are available:
| **Peak type** | **$type** | **Parameters** |
| Fundamental Parameters | fp | |
| Pseudo-Voigt | pv | [//pv_lor E pv_fwhm E//] //pv_lor// is the Lorentzian fraction of the peak profile(s). //pv_fwhm// is the FWHM of the peak profile(s). |
| Split-PearsonVII | spvii | [//h1// E //h2// E //m1// E //m2// E] The sum of //h1// and //h2// gives the FWHM of the composite peak. //m1, m//2 are the PearsonVII exponents of the left and right composite peak, respectively. |
| Split-PseudoVoigt | spv | [//spv_h1// E //spv_h2// E //spv_l1// E //spv_l2// E] The sum of //spv_h1// and //spv_h2// gives the full width at half maximum of the composite peak. //spv_l1, spv_l2//: the Lorentzian fractions of the left and right composite peak, respectively. |
**[//peak_buffer_step// E [//report_on//]]**
As the shapes of phase peaks do not change significantly over a short 2q range, a new peak shape is calculated only if the position of the last peak shape calculated is more than the distance defined by //peak_buffer_step//. Various stretching and interpolation procedures are used in order to calculate in-between peaks. See also section 6.4.
The reserved parameter names of H, K, L, M or parameter names associated with the keywords //sh_Cij_prm// and //hkl_angle// when used in the peak convolution equations result in irregular peak shapes over short 2q ranges and thus a separate peak shape is calculated for each peak.
When defined //report_on// causes the display of the number of peaks in the peaks buffer.
//peak_buffer_step// is set to 500*//Peak_Calculation_Step// by default.
**[//penalty// !E]...**
Defines a penalty function that can be a function of other parameters. Penalties are useful for stabilizing refinements as in for example their use in bond-length restraints.
Example HOCK.INP uses penalties to minimize on the Hock and Schittkowski problem number 65 function.
prm x1 1 min -4.5 max 4.5 val_on_continue = Rand(-4.5, 4.5); del .01
prm x2 1 min -4.5 max 4.5 val_on_continue = Rand(-4.5, 4.5); del .01
prm x3 1 min -5.0 max 5.0 val_on_continue = Rand(-5.0, 5.0); del .01
' Hock and Schittkowski problem number 65 function
penalty = (x1-x2)^2 + (1/9) (x1 + x2 - 10)^2 + (x3 - 5)^2; : 0
prm contraint_1 = x1^2 + x2^2 + x3^2;
penalty = If(contraint_1 < 48, 0, (contraint_1-48)^2); : 0
The next example applies a User defined penalty function to lattice and crystallite size parameters, which are expected to be 5.41011 Å and 200 nm respectively:
str...
Cubic(lp_ceo2 5.41011)
penalty = (lp_ceo2-5.41011)^2;
CS_L(cs_l, 200)
penalty =(cs_l-200)^2;
Minimizing on penalty functions in the presence of observed data is possible with the use of the //only_penalties// keyword.
**[//penalties_weighting_K1// !E]**
Defines the weighting K1 given to penalty functions as defined in Eq. (5‑2). //penalties_weighting_K1// is set to 1 by default.
**[//percent_zeros_before_sparse_A// #]**
Defines the percentage of the A matrix than can be zero before sparse matrix methods are invoked. The default value is 60%.
**[//phase_MAC// !E]**
Calculates the mass absorption coefficient in cm2/g for the current phase. See description for //[[#k038|mixture_MAC]]//.
**[//phase_out// $file [//append//] ]...**
Used for writing phase dependent details to file. See the keyword //out// for a description of //[[#k045|out_record]]//. The Create_hklm_d_Th2_Ip_file uses //phase_out//.
**[//pk_xo// E]**
Provides a mechanism for transforming peak position to an x-axis position. For example, the peak position for neutron time-of-flight data is typically calculated in time-of-flight space, tof, or:
tof = t0 + t1 dhkl + t2 dhkl2
where t0 and t1 and t2 are diffractometer constants. //pk_xo// can be used to refine TOF data as shown in examples TOF_Balzar_sh1.inp and TOF_Balzar_br1.inp.
**[//phase_name// $phase_name]**
The name given to a phase; used for reporting purposes.
**[//phase_penalties//** **$sites N]...****[//hkl_Re_Im// #h #k #l #Re #Im]...**
**[//accumulate_phases_and_save_to_file// $file]**
**[//accumulate_phases_when// !E]**
//phase_penalties// for a single hkl is defined as follows:
{{techref_files:image162.gif?444x50}}where {{techref_files:image164.gif?21x29}}= assigned phase, {{techref_files:image166.gif?20x25}}= calculated phase, Ic = calculated intensity and //d// is the reflection d-spacing. The name N returns the sum of the //phase_penalties// and it can be used in equations and in particular //penalty// equations. {{techref_files:image166.gif?20x25}} is calculated from sites identified in [[#k142|$sites]].
#h, #k, #l are user defined hkls; they are used for formulating the phase penalties. #Re and #Im are the real and imaginary parts of {{techref_files:image164.gif?21x29}}. An example use of phase penalties (see examples AE14-12.INP and AE5-AUTO.inp) is as follows:
penalty = pp1;
phase_penalties * pp1
load hkl_Re_Im
{
0 1 2 1 0
1 0 -2 1 0
1 -2 -1 1 0
}
hkls chosen for phase penalties should comprise those that are of high intensity, large d-spacing and isolated from other peaks to avoid peak overlap. Origin defining hkls are typically chosen.
//accumulate_phases_and_save_to_file// saves the average phases collected to $file//.// Phases are collected when //accumulate_phases_when// evaluates to true; //accumulate_phases_when// defaults to true. Here’s an example use:
temperature 1
temperature 1
temperature 1
temperature 1
temperature 10
...move_to_the_next_temperature_regardless_of_the_change_in_rwp
accumulate_phases_and_save_to_file SOME_FILE.TXT
accumulate_phases_when = T == 10;
Here phases with the best Rwp since the last accumulation are accumulated when the current temperature is 10.
** [//process_times//]**
Displays process times on termination of refinement.