GENERAL DERIVATIVE RELATIONS FOR ANHARMONIC-FORCE FIELDS

The brace notation, introduced by Alien and Csaszar (1993, J. chem. Ph ys., 98, 2983), provides a simple and compact way to deal with derivat ives of arbitrary non-tensorial quantities. One of its main advantages is that it builds the permutational symmetry of the derivatives direc tly into the formalism. The brace notation is applied to formulate the general nth-order Cartesian derivatives of internal coordinates, and to provide closed forms for general, nth-order transformation equation s of anharmonic force fields, expressed as Taylor series, from interna l to Cartesian or normal coordinate spaces.