RMCProfile: NEUTRON_COEFFICIENTS

[HankunXu]

Hi, all,

"NEUTRON_COEFFICIENTS" is explicitly used as a subordinate keyword for "NEUTRON_REAL_SPACE_DATA" and "NEUTRON_RECIPROCAL_SPACE_DATA",

So, what about "XRAY_RECIPROCAL_SPACE_DATA",
          
         (1) The subordinate keywords under the main keyword are directly entered as "NEUTRON_COEFFICIENTS";

   

Code:

XRAY_RECIPROCAL_SPACE_DATA ::
  > FILENAME :: 1.dat
  > DATA_TYPE :: F(Q)
  > FIT_TYPE :: F(Q)
  > FITTED_SCALE
  > NEUTRON_COEFFICIENTS:: 0.01510    0.00547    0.19228    0.00049    0.03480    0.61196       
  > CONVOLVE ::
  > RECIPROCAL_SPACE_FIT :: 1 1110 1
  > RECIPROCAL_SPACE_PARAMETERS :: 1 1110 0.003
  > REAL_SPACE_FIT :: 100 1600 1
  > REAL_SPACE_PARAMETERS :: 100 1600 2000

          (2) or do we need to change the major keyword as "NEUTRON_RECIPROCAL_SPACE_DATA", i.e., nominally for the neutron, but actually for xray ?

   

Code:

NEUTRON_REAL_SPACE_DATA :: 1
  > FILENAME ::1.dat
  > DATA_TYPE :: D(r)
  > FIT_TYPE :: D(r)
  > START_POINT :: 100
  > END_POINT :: 1600
  > CONSTANT_OFFSET ::   0.0000
  > WEIGHT ::   0.015
  > NEUTRON_COEFFICIENTS:: 0.01510    0.00547    0.19228     0.00049 0.03480    0.61196
  > NO_FITTED_OFFSET
  > FITTED_SCALE

"NEUTRON_COEFFICIENTS" would be the best choice if we want to distinguish the same element at different sites.

Thanks

[y8z-admin]

Hi Hankun,

Here are several things worth mentioning,

1. The 'NEUTRON_COEFFICIENTS' is not necessary to be there since we have implemented those coefficients in RMCProfile. Unless you have some speical situations where you do need to explicitly specify the coefficients (e.g., you have some special isotope that is not available in our implemented table), you don't have to have the keyword there.

2. For X-ray, we are now calculating the signal in the true X-ray way, i.e., we will be using the X-ray form factors for the calculation and therefore again, we don't need the 'NEUTRON_COEFFICIENTS' keyword. Also, we do have the new implementation for X-ray calculation for quite a while, in which users only need to provide the reciprocal space data and the Fourier transform will be performed internally in RMCProfile. Details can be found in the manual, https://rmcprofile.ornl.gov/manual/

3. You can also find an X-ray example in our tutorial -- see the 'ex_6' as in the shipped RMCProfile package.

Please let me know if any further issues or any help needed.

Cheers,
Yuanpeng