Path integral Monte Carlo study of CO2 solvation in He4 clusters

Abstract

We present a finite temperature quantum mechanical study of the dynamical and structural properties of small (4)He(N)-CO(2) clusters (N< or =17) using a path integral Monte Carlo (PIMC) method. The simulations were based on a He-CO(2) interaction potential with explicit dependence on the asymmetric stretch of the CO(2) molecule obtained at the CCSD(T) level. The shift of the CO(2) antisymmetric stretching (nu(3)) band origin and effective rotational constant were calculated as a function of the cluster size. In excellent agreement with experimental observations, the CO(2) 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.

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

“…It is clear from this figure that, in Ar 5 −CO 2 , only a part of the argon atoms are located at the T-shaped region, which is different from the donut structure of He 5 −CO 2 . 40 The distinctive distributions could be understood in terms of the strong competition between Ar−Ar and Ar−CO 2 interactions in the formation of clusters. Such competition also leads to obvious structural changes in the evolution of the size of clusters, such as the distortion of the five-membered ring in the evolution from N = 13 to 14, while for the doped helium clusters such changes are much more sluggish.…”

Quantum rotation of Rb2 (3 Σ u + ) attached to HeN droplets: a path-integral Monte Carlo study

“…Motivated by their unique properties as an ideal matrix to perform spectroscopic measurements at low temperature, helium nanodroplets have been the subject of numerous theoretical works in the last decades. In particular path integral Monte Carlo (PIMC) simulations have investigated solvated rotating impurities such as N 2 O [1][2][3][4], HCCH [5], HCCCN [6], OCS [5,7,8] or CO 2 [2,9,10] embedded in He N clusters in order to explore superfluidity effects as a function of the cluster size N at T <1 K. Within the large diversity of possible impurities, alkali dimers have also received a great deal of interest. A wide variety of methods ranging between diffusion Monte Carlo (DMC) [11][12][13][14][15], quantum dynamical calculations [16][17][18][19], variational [13], PIMC treatments [20][21][22] or density functional formalism [23] have been applied to investigate structural and dynamical properties of these He N -X systems.…”

Superfluid response of 4HeN–N2O clusters probed by path integral Monte Carlo simulations

“…As has been observed for other families of He-solvated chromophores (e.g., He N -OCS [59][60][61] and He N -CO 2 [27,33,62]), the first few He atoms form a ''donut'' structure, occupying equatorial positions around the linear impurity molecule, due to the deep Tshaped He-molecule potential minimum. Once that first ring of five solvent atoms is filled, additional helium atoms start to form a second ring in the region near the terminal O atom of the N 2 O impurity, supported by the collinear minimum.…”