A new method to calculate B-matrix elements for external rotations with application to the B-matrix internal coordinate molecular dynamics formalism

B-matrix elements for external rotations are conventionally computed by imp osing the Casimir-Eckart condition (CEC). However, this results in matrix e lements that not only depend on atomic masses but also on the choice of a m oving coordinate frame. A new method to directly calculate the B-matrix ele ments for external rotations, which avoids these problems, is therefore int roduced. An underlying symmetry relation is used to reduce the number of re quired computations. This method is applied to the dynamics equation in non redundant generalized coordinates, which enhances the efficiency of the B-m atrix internal coordinate molecular dynamics formalism. (C) 2001 Elsevier S cience B.V. All rights reserved.