A quantum propagator for path-integral simulations of rigid molecules

The expression for the quantum propagator for rigid tops, proposed by Muser and Berne [Phys. Rev. Lett. 77, 2638 (1996)], has been extended to asymmetric tops. Path-integral Monte Carlo simulations are provided that show that the quantum propagator proposed in this work exactly reproduces the rotational energy of free asymmetric tops as evaluated from the partition function. This propagator can subsequently be used in path-integral simulations of condensed phases if a rigid molecular model is used. (C) 2011 American Institute of Physics. [doi:10.1063/1.3544214]