We report the implementation of a previously suggested method to constrain a molecular system to have mode-specific vibrational energy greater than or equal to the zero-point energy in quasiclassical trajectory calculations [J. M. Bowman, J. Chem. Phys. 91, 2859 (1989); W. H. Miller, J. Chem. Phys. 91, 2863 (1989)]. The implementation is made practical by using a technique described recently [G. Czakó and J. M. Bowman, J. Chem. Phys. 131, 244302 (2009)], where a normal-mode analysis is performed during the course of a trajectory and which gives only real-valued frequencies. The method is applied to the water dimer, where its effectiveness is shown by computing mode energies as a function of integration time. Radial distribution functions are also calculated using constrained quasiclassical and standard classical molecular dynamics at low temperature and at 300 K and compared to rigorous quantum path integral calculations.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry