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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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Photogenerated Quartet State Formation in a Compact Ring-Fused Perylene-Nitroxide.

TL;DR: This paper presents both ultrafast transient absorption experiments and time-resolved EPR (TREPR) studies to probe the spin dynamics of photoexcited PerNO(•) and utilize X-ray crystallography to probe The ability to control both the structure and electronic properties of molecules having multiple spins is important for implementing effective molecule-based spintronics.
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The Variationally Orbital-Adapted Configuration Interaction Singles (VOA-CIS) Approach to Electronically Excited States.

TL;DR: This work shows that in the ground-state geometry, VOA-CIS performs comparably to CIS(D) at predicting relative excited state energies, and correctly rebalances the energy of charge-transfer states versus non-CT states, while simultaneously producing smooth PESs-including the important case of avoided crossings.
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A quantitative quantum-chemical analysis tool for the distribution of mechanical force in molecules

TL;DR: The JEDI (Judgement of Energy DIstribution) analysis is introduced, which is the first quantum chemical method that provides a quantitative understanding of the distribution of mechanical stress energy among all degrees of freedom in a molecule.
Journal ArticleDOI

Proton transfer or hemibonding? The structure and stability of radical cation clusters

TL;DR: It is found that proton transfer based structures are preferred by the (NH3)n˙(+), (H2O)n\.’(+) and (HF)n⩽(+) clusters while hemibonded structures are favoured by (PH3) n˙ (+),(H2S)nˈ’ (+) and(HCl)nͽ(+).
Journal ArticleDOI

Geminal model chemistry III: Partial spin restriction

TL;DR: An ab initio electronic structure model that uses partial spin restriction is defined, which is an intermediate case between the so-called spin-restricted and spin-unrestricted formulations, which are popular in electronic structure methodology.
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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TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
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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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