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Advances in methods and algorithms in a modern quantum chemistry program package

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TLDR
Specific developments discussed include fast methods for density functional theory calculations, linear scaling evaluation of energies, NMR chemical shifts and electric properties, fast auxiliary basis function methods for correlated energies and gradients, equation-of-motion coupled cluster methods for ground and excited states, geminal wavefunctions, embedding methods and techniques for exploring potential energy surfaces.
Abstract
Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package, together with illustrative timings and applications. Specific developments discussed include fast methods for density functional theory calculations, linear scaling evaluation of energies, NMR chemical shifts and electric properties, fast auxiliary basis function methods for correlated energies and gradients, equation-of-motion coupled cluster methods for ground and excited states, geminal wavefunctions, embedding methods and techniques for exploring potential energy surfaces.

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Angle resolved photoemission from organic semiconductors: orbital imaging beyond the molecular orbital interpretation

TL;DR: In this article, a combined theoretical and experimental study was conducted to compare a Dyson-orbital and a molecular-orbitals-based interpretation of angle resolved photoemission spectroscopy (ARPES).
Journal ArticleDOI

Exchange coupling constants using Density Functional Theory: long-range corrected functionals.

TL;DR: This study shows that some of the long‐range corrected functionals tested give promising results in the calculation of the exchange coupling constants of a number of transition metal dinuclear complexes.
Journal ArticleDOI

Spectral tuning of rhodopsin and visual cone pigments

TL;DR: Using large-scale quantum chemical calculations at the density functional theory level combined with frozen density embedding theory, it is shown how the protein environment of vision pigments tunes the absorption of retinal by electrostatically dominated interactions between the chromophore and the surrounding protein residues.
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Structural progression in clusters of ionized water, (H2O)n=1-5(+).

TL;DR: Structures, properties, and relative energies are presented for oxidized water clusters, (H2O)n=1-5(+), using equation-of-motion coupled-cluster theory approaches, which reveal that preferential solvation of the hydronium cation by water serves as the dominant driving force for this pair separation.
Journal ArticleDOI

Chlorinated polyketide obtained from a Daldinia sp. treated with the epigenetic modifier suberoylanilide hydroxamic acid.

TL;DR: During the course of these studies it was determined that metabolite 2 and the previously reported daldinone B shared the same spectroscopic data, leading to a revision of the reported structure.
References
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Journal ArticleDOI

Density‐functional thermochemistry. III. The role of exact exchange

TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Journal ArticleDOI

Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen

TL;DR: In this paper, a detailed study of correlation effects in the oxygen atom was conducted, and it was shown that primitive basis sets of primitive Gaussian functions effectively and efficiently describe correlation effects.

疟原虫var基因转换速率变化导致抗原变异[英]/Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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Journal ArticleDOI

General atomic and molecular electronic structure system

TL;DR: A description of the ab initio quantum chemistry package GAMESS, which can be treated with wave functions ranging from the simplest closed‐shell case up to a general MCSCF case, permitting calculations at the necessary level of sophistication.
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