Path integral Monte Carlo study of CO2 solvation in 4He clusters.

We present a finite temperature quantum mechanical study of the dynamical and structural properties of small 4HeN–CO2 clusters (N≤=17) using a path integral Monte Carlo (PIMC) method. The simulations were based on a He–CO2 interaction potential with explicit dependence on the asymmetric stretch of the CO2 molecule obtained at the CCSD(T) level. The shift of the CO2 antisymmetric stretching (ν3) band origin and effective rotational constant were calculated as a function of the cluster size. In excellent agreement with experimental observations, the CO2 vibrational band origin shifts and rotational constant show a turnaround near N=5, corresponding to a donut structure with the He atoms in equatorial positions of the linear dopant molecule [ABSTRACT FROM AUTHOR]