Self correlations in gases of linear molecules with application to thermal-neutron scattering

A phenomenological linear Boltzmann equation is derived to study the classical motion of a rigid linear test molecule in a gaseous medium. The state of the molecule is defined by its center- of-mass coordinate and velocity, rotation frequency, orientation of its angular momentum and a rotor phase angle. The thermal-neutron scattering cross section is derived from a Fourier transform of a density distribution function which satisfies the Boltzmann equation with a suitable initial condition. Cross sections are calculated for some models to indicate the effect of coupling of center of mass and internal behavior.