Knowledge Bank

Recent $successes1$ in calculating the vibrational frequencies for polyatomic molecules have encouraged us to try extending this calculational method to the latest semi-empirical hamiltonians. Using the scaled quantum mechanical force field method developed by Pulay $etal.2$, the force fields calculated by the Austin Method 1 (AMI) hamiltonian were scaled. The vibrational frequencies obtained from these scaled force fields yielded good agreement with the observed frequencies. The results for benzene, 9,10-dihydroanthracene, and other selected molecules will be presented.