Thompson-cox-hastings Pseudo-voigt Function -

[ V_\textTCH(x) = \eta , L(x) + (1-\eta) , G(x) ]

[ \eta = 1.36603 \left( \frac\Gamma_L\Gamma_V \right) - 0.47719 \left( \frac\Gamma_L\Gamma_V \right)^2 + 0.11116 \left( \frac\Gamma_L\Gamma_V \right)^3 ] thompson-cox-hastings pseudo-voigt function

return (1-eta)*G + eta*L P. Thompson, D. E. Cox, and J. B. Hastings, “Rietveld refinement of Debye–Scherrer synchrotron X‑ray data from Al₂O₃” , J. Appl. Cryst. (1987), 20, 79–83. The empirical FWHM and mixing coefficient formulas are given there. [ V_\textTCH(x) = \eta , L(x) + (1-\eta)