Journal ArticleDOI
Biorthogonal valence bond descriptions of electronic structure
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In this paper, a valence bond approach based on nonorthogonal orbitals in a biorthogonal representation is presented, which suffers from the lack of a variational bound on the energy functional, but with a suitable optimization of the orbitals reliable molecular wavefunctions can be obtained.Abstract:
A valence bond approach based on nonorthogonal orbitals in a biorthogonal representation is presented. While the scheme suffers from the lack of a variational bound on the energy functional, it is shown that with a suitable optimization of the orbitals reliable molecular wavefunctions can be obtained. A review of the background theory is given emphasizing the similarity of this approach to the familiar spin-free unitary group formulation of quantum chemistry. The details of the computer implementation are discussed and the method is illustrated with model calculations on HF, H2O and F2O2.read more
Citations
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A survey of recent developments in ab initio valence bond theory
Philippe C. Hiberty,Sason Shaik +1 more
TL;DR: This review aims at summarizing the most important developments of ab initio valence bond methods during the last two or three decades, and is primarily devoted to a description of what the various methods can actually achieve within their specific scopes and limitations.
Journal ArticleDOI
Combining Multiconfigurational Wave Functions with Density Functional Estimates of Dynamic Electron Correlation
TL;DR: In this paper, the authors proposed a method based on partitioning the electrons of a system into two sets and applying a wave function description to one set while obtaining the correlation of the second set and the interaction between sets from a density functional.
Journal ArticleDOI
A Nonorthogonal State-Interaction Approach for Matrix Product State Wave Functions
TL;DR: The key element is the transformation of the MPS wave functions of different states from a nonorthogonal to a biorthonormal molecular orbital basis representation by exploiting a sequence of nonunitary transformations, following a proposal by Malmqvist.
Journal ArticleDOI
Novel methods for configuration interaction and orbital optimization for wave functions containing non-orthogonal orbitals with applications to the chromium dimer and trimer
TL;DR: A novel algorithm for performing configuration interaction (CI) calculations using non-orthogonal orbitals is introduced, which allows expressing the CI-vector in a bi-orthonormal basis, thereby drastically reducing the computational complexity.
Journal ArticleDOI
On the importance of orbital localization in QC-DMRG calculations
TL;DR: In this paper, the authors investigated the importance of orbital localization in the application of the Density Matrix Renormalization Group (DMRG) technique to ab initio studies of molecular electronic structure.
References
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Journal ArticleDOI
The influence of polarization functions on molecular orbital hydrogenation energies
P. C. Hariharan,John A. Pople +1 more
TL;DR: In this paper, a split-valence extended gaussian basis set was used to obtain the LCAO-MO-SCF energies of closed shell species with two non-hydrogen atoms.
Book
Advanced Inorganic Chemistry
TL;DR: Cotton and Wilkinson's Advanced Inorganic Chemistry (AIC) as discussed by the authors is one of the most widely used inorganic chemistry books and has been used for more than a quarter century.
Journal ArticleDOI
Gaussian‐Type Functions for Polyatomic Systems. II
Sigeru Huzinaga,Catalina Arnau +1 more
TL;DR: In this article, the use of a linear combination of Gaussian type orbitals (CGTO) instead of an individual Gaussian-type orbital (GTO) as a unit of basis functions for large-scale molecular calculations is discussed.
Journal ArticleDOI
XXXIV. Notes on the molecular orbital treatment of the hydrogen molecule
TL;DR: In this paper, the molecular orbital treatment of the hydrogen molecule is discussed and discussed in detail, and a discussion of the relationship between the molecular orbit treatment and the physical properties of the molecule is presented.