Mean Amplitudes of Vibration in Allene and Allene-d4 Molecules. I

Observed fundamentals for allene and allene-d4 are used for performing a normal coordinate analysis. Eight alternative sets of 13 force constants from the harmonic potential energy function are evaluated numerically. The normal coordinates for allene and allene-d4 are determined. Analytical expressions for all the seven types of interatomic distance displacements are given. For each of these types, both in allene and allene-d4, the standard deviations (here called mean amplitudes of vibration) are calculated. The obtained values at four temperatures, T = 0, 273, 298, and 323 °K, are reported.