Molecular electric quadrupole moments calculated with matrix dressed SDCI

Abstract

We have calculated the molecular electric quadrupole moment (MEQM) for the set of molecules N 2 , C 2 H 2 , CO, CO 2 , CS 2 , HF, and BH. We have used SR-SDCI and ðSCÞ 2 -SR-SDCI methods and we have compared our results with high-level theoretical ones, including FCI values for HF and BH, and with experimental values. The calculated MEQM provides a test of the effect that the energy converged ðSCÞ 2 dressing method brings to the SDCI wavefunctions. The results suggest that the ðSCÞ 2 -SR-SDCI method can be a cost-effective and quite accurate method for the calculation of post-SCF effects on electric quadrupole moments. Ó

Linewidths of C2H2 perturbed by H2: experiments and calculations from an ab initio potential

“…[26,61] The C 2 H 2 -H 2 potential is deeper and more anisotropic than the N 2 -H 2 potential. We infer that this is due to the fact that the magnitude of the quadrupole moment of the acetylene is roughly 4.5 times [62,63] the quadrupole of N 2 , [61] and that the polarizability as well as the anisotropic polarizability of the acetylene are larger for acetylene (roughly twice) than for nitrogen. [61,63] The anisotropy at short range is greater for C 2 H 2 -H 2 because the acetylene molecule is longer than the nitrogen molecule.…”

Molecular electric moments calculated by using natural orbital functional theory

“…We compare the obtained PNOF6 results with the experimental values reported in the literature [6,10,11,[25][26][27][28], as well as with the theoretically computed values of Bundgen et al who used the multi-reference single and double excitation configuration interaction (MRSD-CI) method, and the coupled-cluster single and doubles (CCSD) values calculated by us. Recall that the CCSD values for one-electron properties differ from full-CI results in only 2% if no multiconfigurational character is observed [29], so they can be considered as benchmark calculations.…”

“…For comparison, we have included the available experimental data, and the calculated Hartree-Fock (HF) and CCSD values using the GAMESS program [38,39]. The experimental equilibrium geometries [10,11,42,44] have been used to carry out all calculations. The performance of theoretically obtained results is established by carrying out a statistical analysis of the mean absolute errors (MAE) with respect to the experimental data.…”

“…Theoretical calculations are therefore essential but challenging for quantum chemistry methods. The accurate calculation of these properties is highly dependent on the method employed [8], either regarding approximate density functionals [9] or methods based on wavefunctions [10,11]. Consequently, calculating the multipole moments is a way to assess any electronic structure method.…”

Simultaneous dipole and quadrupole moment contribution in the Bogoliubov spectrum: Application of the non-integral Gross–Pitaevskii equation

“…For particles of mass m = 4.3 10 −23 g and quadrupole moment Q = 6 DebyeÅ (acetylene molecules [19]) at the particle concentration n 0 ∼ 10 14 cm −3 quadrupolar term is about 0.001 of the quantum Bohm potential. Alkaline diatoms have larger mass and larger electric quadrupole moment (∼ 50 DebyeÅ [23] In this paper we are interested in the BECs of particles possessing the dipole and quadrupole moments simultaneously.…”