Experimental Observable Options

Options for predicting experimental observables are found below.

Currently implemented observables are pair distribution functions, powder x-ray diffraction, powder neutron diffraction and x-ray photoelectron spectra.

do_xrd                      = .true.     # Do X-Ray diffraction prediction 
q_range_min                 =   1.0      # -> Range for the XRD/structure factor 
                                         #    calculation: q = 4 pi sin( theta ) 
                                         #    / lambda, where theta is the half 
                                         #    angle of diffraction
q_range_max                 =  10.0      # -> Range - " - 
write_xrd                   = .true.     # -> Write out xrd pattern
xrd_output                  = 'q*F(q)'   # -> Output the XRD pattern as the direct
                                         #    Fourier transform of G(r), the reduced 
                                         #    PDF (this can be 'F(q)'/'i(q)' or 
                                         #    the full xrd intensity 'xrd')

do_pair_distribution        = .true.     # Calculate the XRD from the pair 
                                         # distribution function, so it scales 
                                         # linearly with the number of atoms
pair_distribution_kde_sigma =   0.1      # -> Use Gaussian Kernel Density Estimate 
                                         #    of width 0.1A to smooth out, 
                                         #    accounting for thermal broadening
pair_distribution_partial   = .true.     # -> Calculate partial pair-distribution functions
pair_distribution_rcut      =  10.6      # -> Cutoff partial pair distribution 
r_range_min                 =   0.1      # -> Range for the PDF calculation   
r_range_max                 =  10.0      # -> Range - " - 
write_pair_distribution     = .true.     # -> Write out pair distribution functions 

do_structure_factor         = .true.     # Use (raw, non-scattering factor corrected)
                                         # (partial) structure factor(s) for calculations 
structure_factor_from_pdf   = .true.     # -> Fourier transform the pair distribution 
                                         #    functions to obtain the uncorrected structure
                                         #    factors, which when corrected give the XRD pattern. 
structure_factor_window     = .true.     # -> Use a multiplicative "windowing" function
                                         #    (sin(pi r / r_cut)/(pi r / r_cut)) in the fourier
                                         #    transform of pdf to minimize high frequency 
                                         #    artifacts resulting from the finite range Fourier
                                         #    transform.
write_structure_factor      = .true.     # -> Write out structure factors

do_xps = .true.                          # Do x-ray photoelectron spectroscopy (XPS) prediction if 
                                         # a model has been specified in the .gap file
xps_e_min = 280.                         # Minimum of range for XPS prediction
xps_e_max = 300.                         # Maximum of range for XPS prediction
xps_n_samples = 301                      # Number of samples for XPS prediction