Many-body calculations of molecular electric polarizabilities in asymptotically complete basis sets

Abstract

International audienceThe static dipole polarizabilities of Ne, CO, N2, F2, HF, H2O, HCN, and C2H2 (acetylene) have been determined close to the Full-CI limit along with an asymptotically complete basis set (CBS), according to the principles of a Focal Point Analysis. In this purpose we employed the results of Finite Field calculations up to the level of Coupled Cluster theory including Single, Double, Triple, Quadruple and perturbative Pentuple excitations [CCSDTQ(P)], in conjunction with suited extrapolations of energies obtained using augmented and doubly-augmented Dunning's correlation consistent polarized valence basis sets of improving quality. The polarizability characteristics of C2H4 (ethylene) and C2H6 (ethane) have been determined on the same grounds at the CCSDTQ level in the CBS limit. Comparison is made with results obtained using lower levels in electronic correlation, or taking into account the relaxation of the molecular structure due to an adiabatic polarization process. Vibrational corrections to electronic polarizabilities have been empirically estimated according to Born-Oppenheimer Molecular Dynamical simulations employing Density Functional Theory. Confrontation with experiment ultimately indicates relative accuracies of the order of 1 to 2 %

Insights into the dynamics of evaporation and proton migration in protonated water clusters from Large‐scale Born–Oppenheimer direct dynamics

“…The BLYP/6‐31+G(d,p) calculation predicts the former to be 2.17 D and the isotropic polarizability to be 7.5 a.u. The dipole moment of water is known to be 1.85 D.[54] Regarding the polarizability, its isotropic value, according to experiment[55] and high‐level ab initio calculations[56] is 9.5 a.u. Our calculations are, therefore, not quantitatively accurate but qualitatively correct with respect to long‐range interactions.…”

Straightening the Hierarchical Staircase for Basis Set Extrapolations: A Low-Cost Approach to High-Accuracy Computational Chemistry

“…Dual-level (triple-level for HF) CBS extrapolations of polarizabilities were also reported for tetravalent actinide ions (126) with ae-relativistic core-correlation bases, and at the triple level with AVX Z and dAVX Z (X = Q, 5, 6). Moreover, calculations of static dipole polarizabilities were performed for Ne, CO, N 2 , F 2 , HF, H 2 O, HCN, and C 2 H 2 at the CBS level by focal-point analysis (127). Because the above procedure requires four correlated calculations with applied electric fields and one without for two cardinal numbers (83), the method is expensive, and hence we next consider a simpler variant.…”

Theoretical study of molecular vibrations in electron momentum spectroscopy experiments on furan: An analytical versus a molecular dynamical approach

“…BOMD 74-76 is a method of choice for unravelling the effects of thermally induced nuclear motions on molecular properties, such as static dipole-dipole electric polarizabilities 89,90 or electron momentum distributions, 62,77,78 to cite just a few. Molecular properties are thermally averaged by classical propagation of the nuclear degrees of freedom based on quantum mechanically computed forces (ab initio BOMD 91,92 ).…”

“…84,85 Homemade C-shell scripts have been used to automatically convert the molecular coordinates output of the BOMD//ωB97XD/aug-cc-pVDZ runs into input for further B3LYP/aug-cc-pVTZ calculations of the electronic structure, using the GAUSSIAN09 package of programs, 97 and to ultimately combine results for thermally averaging (e,2e) electron momentum profiles obtained by means of the MOMAP program by Brion and coworkers. 89 In order to enable physically meaningful comparisons with experiment, the theoretical spherically averaged momentum distributions have been convoluted with the experimental momentum resolution, using the approach by Migdall et al 98…”