| Abstract: | We present a new software package for the theoretical treatment of anharmonic vibrational spectra of nonlinear polyatomic molecules. The package, called “B&D,” computes vibrational energies starting from sets of force constants defined as potential energy derivatives. The method employed allows us to combine experimental rotation-vibration data with any information made available from ab initio calculations. The package follows the natural procedure in which a molecular problem is solved, both in the symbolic construction of Hamiltonian operator and basis functions and in the numerical computation of the Hamiltonian matrix elements. The novelty consists in making the entire procedure fully automatic, so that the occurrence of errors is greatly reduced and the laborious process involved in deriving and implementing the Hamiltonian is dramatically simplified. © 1999 John Wiley & Sons, Inc. J Comput Chem 20: 1716–1730, 1999 |
