Non-Gaussian Effects in Thermal-Neutron Scattering in Liquid Argon

Abstract

The Non-Gaussian corrections have been estimated for liquid argon by using a model in which the motion of a typical atom is analyzed in terms of the dynamics of an “oscillation”, a quasiparticle consisting of the atom plus a surrounding spherical shell representing the collective effect of the instantaneous near neighbours. Tne oscillatory motion of the atom inside the shell is represented by a stochastic Langevin oscillator first used by Rahman, Singwi and Sjolander. As regards the diffusive motion of the atom plus the spherical shell, a Langevin binary collision model is used. Comparison with Rahman’s calculations for liquid argon shows that the agreement of velocity autocorrelation and α₂(t) has been considerably improved with the present model in comparison with the earlier Gibbs model.