An efficient approach for calculating vibrational wave functions and zero-point vibrational corrections to molecular properties of polyatomic molecules

Abstract

Articles you may be interested inA virtual vibrational self-consistent-field method for efficient calculation of molecular vibrational partition functions and thermal effects on molecular properties Density functional self-consistent quantum mechanics/molecular mechanics theory for linear and nonlinear molecular properties: Applications to solvated water and formaldehyde Analytic calculation of first-order molecular properties at the explicitly correlated second-order Møller-Plesset level: Basis-set limits for the molecular quadrupole moments of BH and HFWe have recently presented a formalism for calculating zero-point vibrational corrections to molecular properties of polyatomic molecules in which the contribution to the zero-point vibrational correction from the anharmonicity of the potential is included in the calculations by performing a perturbation expansion of the vibrational wave function around an effective geometry. In this paper we describe an implementation of this approach, focusing on computational aspects such as the definition of normal coordinates at a nonequilibrium geometry and the use of the Eckart frame in order to obtain accurate nonisotropic molecular properties. The formalism allows for a black-box evaluation of zero-point vibrational corrections, completed in two successive steps, requiring a total of two molecular Hessians, 6K -11 molecular gradients, and 6K -11 property evaluations, K being the number of atoms. We apply the approach to the study of a number of electric and magnetic properties-the dipole and quadrupole moments, the static and frequency-dependent polarizability, the magnetizability, the rotational g tensor and the nuclear shieldings-of the molecules hydrogen fluoride, water, ammonia, and methane. Particular attention is paid to the importance of electron correlation and of the importance of the zero-point vibrational corrections for obtaining accurate estimates of molecular properties for a direct comparison with experiment.

Dispersion corrected DFT approaches for anharmonic vibrational frequency calculations: nucleobases and their dimers

“…On the contrary, consistent procedures can be derived from QM computations of vibrational properties beyond the harmonic approximation. Recently, exact solutions for the treatment of few active modes to the vibrational problem for a generic system has been proposed 55 and effective schemes to compute vibrational frequencies within the second order vibrational perturbative (VPT2) [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] or vibrational self-consistent field (VSCF) based [76][77][78][79][80][81][82][83][84][85] approaches have been developed and implemented. In particular, a general VPT2 framework to compute thermodynamic properties, vibrational energies and transition intensities from the vibrational ground state to fundamentals, overtones and combination bands 66,67,[86][87][88] has been developed in our group.…”

Benchmarking density-functional-theory calculations of rotational g tensors and magnetizabilities using accurate coupled-cluster calculations

“…The vibrational corrections were calculated at the B3LYP/aug-cc-pCVTZ level using the method of Ref. 40 and subtracted from the experimental values to give a set of empirical equilibrium values, see 27 In Table I, the errors in rotational g tensors relative to the empirical equilibrium values are presented, excluding the multireference O 3 molecule from the analysis; for the full analysis and individual g-tensor elements, see the supplementary material. 27 An inspection of the table shows that the addition of core-correlating functions to either the standard or augmented basis-set families leads to only modest changes in the results; the addition of diffuse functions is much more important.…”

“…5,11,54 In the present work, we calculate the ZPVCs to the rotational g tensor and the magnetizability using perturbation theory, following Ref. 40 using DFT.…”

“…A variety of methods has been used to calculate these quantities previously, including Hartree-Fock theory, 6,30-32 multiconfigurational self-consistent-field ͑MCSCF͒ theory, [33][34][35][36][37][38][39][40] Møller-Plesset theory, 39 [51][52][53] and DFT. 5,11,54 In the present work, we calculate the ZPVCs to the rotational g tensor and the magnetizability using perturbation theory, following Ref.…”

Gas phase optical rotation calculated from coupled cluster theory with zero‐point vibrational corrections from density functional theory

“…Ruud et al 21 included harmonic and anharmonic effects by a Taylor expansion of [a] to second order about an effective geometry, 51,52 while Mort and Autschbach 22-25 used a minor modification of the general formula of Sauer and Packer. 53 These studies clearly show that vibrational effects are non-negligible and that anharmonic contributions in some cases are more important than harmonic ones.…”