You can choose one of a number of peak profile functions to describe the shape of the window's diffraction peaks. CrystalDiffract also lets you change the peak width (full-width at half-maximum, FWHM). Note that these settings are assumed to be instrument properties, and hence they apply to all simulated patterns in the current window.
Do the following:
Choose a peak function from the Diffraction > Peak Function submenu. Four functions are currently support: Delta Function, Lorentzian, Gaussian and Pseudo-Voigt.
If you are using the Pseudo-Voigt function, you can specify its Eta parameter by choosing Diffraction > Peak Function > Eta and specifying a value in the sheet/dialog that appears.
You can also change the peak shape using the Peak Profile popup in the Instrument group of the Parameters Inspector.
Open the Instrument group in the Parameters Inspector, then do one of the following:
If you are using a constant-wavelength (x-ray or neutron) simulation, or an Energy-Dispersive simulation, you can specify a fixed peak width (Full-Width at Half Maximum) using the Peak Width slider or text controls.
For Time-of-Flight Neutron diffraction simulations, you need to specify the instrument resolution: this is the ratio Δd/d, which describes how the peak width changes with increasing d-spacing (or time-of-flight).
See also