Truncation effects on second moments of vibrational bands

Abstract

The truncation effect on the second moment of a vibrational line shape is examined in detail on the basis of the assumed time correlation function. The magnitude of the effect is evaluated as a function of the line shape parameter and of the truncation limit. The results indicate that the integration has to be carried out more than 50 times as wide as the line width for obtaining an accurate second moment from the direct integration. An approximate method to correct the truncation effect is proposed.