The thermal broadening functions in the Bethe-Placzek approximation, is possible to be present in the form of convolution of one Lorentzian and one Guaussian density. This convolution often named as Voigt-profile or Voigt-function. The computation of this profile is required in several problems arising in a variety of physicochemical subjects, such as nuclear reactors, atmospheric infrared penetrance and several problems of spectroscopy. In this work we suggest using a new formulaes for the calculation of these functions. Our new calculation instruments are representation in the form of finite sums of simple mathematical expressions, based on quadrature formulae, rational approximations and error estimation.
They give the good results for the fast calculations, aimed to neutron resonance spectrometry. These approximations can be realized by simple computer codes.
Keywords: Bethe-Placzek approximation, Complex probability function, Voigt-profile.