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Abstract: The frequency and temperature dependence of dipole-quadrupole polarizability of tetrahedral P4 and adamantane molecules have been studied using first-principle all-electron density functional theory calculation. The recently developed time-dependent auxiliary density functional theory is extended for the calculation of dynamic dipole-quadrupole polarizabilities. Temperature effects are incorporated by Born–Oppenheimer molecular dynamics (BOMD) simulations recorded up to 100ps. The dynamic dipole-quadrupole polarizabilities are calculated along these trajectories. The frequency and temperature effects can be significant for the accurate calculation of dipole-quadrupole polarizability. We have also identified the main reason for the observed discrepancy between experiment and theory in the case of adamantane. [Copyright &y& Elsevier]

Abstract: In this Letter, we present dipole moments and polarizabilities of some open-shell doublet radicals, obtained analytically using constrained variational response to Fock-space (FS) multi-reference (MR) coupled cluster (CC) theory. These radicals can be treated as electron attached (EA) states of the corresponding closed-shell cations. Additionally, we also report analytical polarizabilities of some doublet radicals, which can be considered as ionized (IP) states of the corresponding anions. We compare our results with finite field FSMRCC response and the available benchmark results. [Copyright &y& Elsevier]

A comparative study of dipole moments, polarizabilities and hyperpolarizabilities of 16 different molecules is performed employing two completely different theoretical approaches namely, density functional theory (DFT) and coupled cluster singles and doubles (CCSD). Both methods include electron correlation. The CCSD method is more accurate but highly expensive. DFT with auxiliary density allows non-iterative solutions which is computational advantage and useful for large molecules. Dipole moments and polarizability calculations from DFT are in very good agreement with CCSD calculations. However, negative hyperpolarizability values from DFT differ significantly from their CCSD counterparts, whereas positive hyperpolarizabilities show reasonable agreement between these methodologies. [ABSTRACT FROM AUTHOR]

Abstract: The dipole polarizability is studied for few electron quantum dots using extended coupled cluster linear response method (ECCLR). The polarizability of pure parabolic quantum dots depends only on the number of electrons and the parabolic confinement strength. We added impurity in a Gaussian form to the external parabolic potential and used ECCLR to calculate polarizability. To examine the effect of external potential, we changed the parabolic confinement to square-well and repeated all calculations. We mainly looked at eigenvalue spectrum and charge density specially when the system shifts towards lower density regions. [Copyright &y& Elsevier]

Abstract: Fock-space multi-reference coupled cluster theory is an efficient method for electronic structure of nearly degenerate cases. However, it suffers from the intruder state problem for large model space. The intermediate Hamiltonian formulation eliminates intruder state problem and helps in the convergence of equations. In this paper we have implemented intermediate Hamiltonian approach in Fock-space coupled cluster method for the response properties. We test our method for the dipole moments of doublet radicals. We report dipole moments of CN, SF and NS radicals. [Copyright &y& Elsevier]

Abstract: A Lagrangian approach for electric dipoles within second order Generalized Van Vleck Perturbation Theory (GVVPT2) is presented. The Lagrangian approach for this response property requires that only one, perturbation-independent, set of simultaneous equations needs to be solved. The presented formulation is demonstrated numerically on several well studied molecules at their equilibrium bond lengths and on the complete potential energy curves of the ground and first excited states of LiH. Numerical corroboration of the expected continuity for molecular properties for the GVVPT2 method is observed. It is seen that the GVVPT2 electric dipoles are in good agreement with experiment and with other high accuracy theoretical methods. [Copyright &y& Elsevier]

Abstract: Fock space (FS) multi-reference (MR) coupled-cluster (CC) has been established to be state-of-the-art method for energies of open-shell radicals, ionized, electron attached states and excited states. Due to the multi-root nature of the method, the linear response of MRCC, however, is non-trivial. Constrained variation approach (CVA) makes it plausible to calculate response of the MRCC method efficiently. However, the approach is used for only one root of the problem at a time. In the present article, we make first implementation of the approach and present test results of dipole moments of small radicals. [Copyright &y& Elsevier]

Highlights: [•] Extended coupled cluster method is used for all calculations. [•] The energy functional is truncated up to nth perturbation order. [•] Dipole moments for all the molecules are calculated at both equilibrium and stretched geometry. [Copyright &y& Elsevier]