Journal ArticleDOI
Force Constants and Dipole-Moment Derivatives of Molecules from Perturbed Hartree-Fock Calculations. I
J. Gerratt,Ian Mills +1 more
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TLDR
In this article, the Hartree-Fock wave function was used as an approximate wave function for the direct calculation of force constants and dipole-moment derivatives from SCF-MO wavefunctions.Abstract:
General expressions for the force constants and dipole‐moment derivatives of molecules are derived, and the problems arising in their practical application are reviewed. Great emphasis is placed on the use of the Hartree–Fock function as an approximate wavefunction, and a number of its properties are discussed and re‐emphasised. The main content of this paper is the development of a perturbed Hartree–Fock theory that makes possible the direct calculation of force constants and dipole‐moment derivatives from SCF–MO wavefunctions. Essentially the theory yields ∂φi / ∂RJα, the derivative of an MO with respect to a nuclear coordinate.read more
Citations
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Journal ArticleDOI
Perturbative treatment of scalar-relativistic effects in coupled-cluster calculations of equilibrium geometries and harmonic vibrational frequencies using analytic second-derivative techniques
Christine Michauk,Jürgen Gauss +1 more
TL;DR: The implementation for Hartree-Fock self-consistent field, second-order Moller-Plesset perturbation theory, as well as the coupled-cluster level is used to investigate the relativistic effects on the geometrical parameters and harmonic vibrational frequencies for a set of molecules containing light elements.
Book ChapterDOI
Newton Based Optimization Methods for Obtaining Molecular Conformation
TL;DR: This chapter presents an alternative approach that has the added capability of handling Hessians, which may contain negative eigenvalues, which will prove especially useful for starting geometries, which are well removed from the desired minima.
Journal ArticleDOI
Computational studies of the nonlinear optical properties of organometallic complexes
TL;DR: A brief introduction to the theory of NLO effects is provided, and a summary of the key experimental techniques for the determination of molecular first hyperpolarizabilities is included, with discussion of their advantages and disadvantages as discussed by the authors.
Journal ArticleDOI
Orbital instabilities and spin-symmetry breaking in coupled-cluster calculations of indirect nuclear spin–spin coupling constants
Alexander A. Auer,Jürgen Gauss +1 more
TL;DR: In this article, the effect of orbital instabilities is investigated for spin-symmetry breaking perturbations, namely the Fermi-contact (FC) and spin-dipole (SD) contributions to the indirect nuclear spin-spin coupling constants.
Journal ArticleDOI
A thorough understanding of the nonlinear optical properties of BODIPY/carborane/diketopyrrolopyrrole hybrid chromophores: module contribution, linear combination, one-/two-dimensional difference and carborane's arrangement
TL;DR: In this article, the geometric and electronic structures, electronic absorption spectra, polarizabilities (αave) and first hyperpolarizabilities were calculated using density functional theory, which can be efficiently deduced from the corresponding building blocks.
References
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Book
Dynamical Theory of Crystal Lattices
Max Born,Kʿun Huang +1 more
TL;DR: Born and Huang's classic work on the dynamics of crystal lattices was published over thirty years ago, and it remains the definitive treatment of the subject as mentioned in this paper. But it is not the most complete work on crystal lattice dynamics.
Journal ArticleDOI
Forces in molecules
TL;DR: In this article, it was shown that the force on a nucleus in an atomic system is just the classical electrostatic force that would be exerted on this nucleus by other nuclei and by the electrons' charge distribution.