Finite temperature path integral Monte Carlo simulations of structural and dynamical properties of ArN-CO2 clusters

We report finite temperature quantum mechanical simulations of structural and dynamical properties of Ar-N-CO2 clusters using a path integral Monte Carlo algorithm. The simulations are based on a newly developed analytical Ar-CO2 interaction potential obtained by fitting ab initio results to an anisotropic two-dimensional Morse/Long-range function. The calculated distributions of argon atoms around the CO2 molecule in Ar-N-CO2 clusters with different sizes are consistent to the previous studies of the configurations of the clusters. A first-order perturbation theory is used to quantitatively predict the CO2 vibrational frequency shift in different clusters. The first-solvation shell is completed at N = 17. Interestingly, our simulations for larger Ar-N-CO2 clusters showed several different structures of the argon shell around the doped CO2 molecule. The observed two distinct peaks (2338.8 and 2344.5 cm(-1)) in the v(3) band of CO2 may be due to the different arrangements of argon atoms around the dopant molecule. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4746941]