Session S15 - Materials Theory and Simulation V.
FOCUS session, Wednesday afternoon, March 14
Room 211, Washington State Convention Center
The incorporation of rotational degrees of freedom into Quantum Monte Carlo calculations is necessary for studies of molecular clusters (e.g. water) and molecule doped quantum clusters (e.g. SF_6 in helium).
We describe our recent implementation of importance sampling in rigid body diffusion monte carlo and show that it correctly samples the angular degrees of freedom. We also demonstrate that importance sampling significantly improves the efficiency and accuracy of calculations of ground state properties.
Molecules doped in helium clusters exhibit very interesting rotational spectra that resemble the gas phase spectra with reduced rotational constants (increased moments of inertia). This phenomenon is explored by applying the above methodology to investigate the degree of adiabatic following of the helium density surrounding the SF_6 molecule in SF_6-He_N clusters.
Our results suggest incomplete adiabatic following of the helium density around the SF_6 molecule, even for the smallest cluster sizes.