Theory of vibrational effects on properties of methane and its isotopomers

Abstract

Expressions are presented for calculating the effects of vibrational motion on physical properties of the methane molecule and its isotopomers. The properties considered are of T_d-type symmetry (polarizability, magnetizability and carbon-13 shielding), C _3v -type symmetry (proton shielding and carbon-13-proton spin-spin coupling) and C _2v -type symmetry (proton deuteron spin-spin coupling). The expressions are given in terms of coefficients of the property surfaces expressed in internal coordinates and the [Lbar]-tensor components of the theory of Hoy, Mills and Strey. It is known that some of the second order terms are quite significant. The equations are also applicable to SiH₄, CF₄, NH⁺ ₄ etc. and their isotopomers.