Mass Derivatives of Molecular Parameters and Distortions in r((2))(m) Structures

Expressions are derived for the derivatives of various molecular vibration-rotation parameters with respect to atomic masses. These are applied to determine an expression for the mass derivatives of the zero-point moments of inertia, and hence the theoretical substitution coordinates. It is then possible to calculate the distortions in structures determined by means of the r((2))(m) method. The latter agree well with the distortions found in r((2))(m) fits of synthetic data. Copyright 2001 Academic Press.