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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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Quantitative Structure-Activity Relationship (QSAR) for the Oxidation of Trace Organic Contaminants by Sulfate Radical

TL;DR: The QSAR model provides a robust predictive tool for estimating emerging micropollutants removal using SO4•– during wastewater treatment processes and indicates that compounds in which electron transfer and addition channels dominate tend to exhibit a faster second-order rate constants (kSO4––) than that of H–atom abstraction.
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Optical absorption of small silver clusters: Agn, (n=4–22)

TL;DR: The analysis of the molecular transitions indicates that the s-electrons are responsible for the optical response of small clusters while the d-electron play a crucial role in the optical excitations for larger n values.
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Interfacing Q‐Chem and CHARMM to perform QM/MM reaction path calculations

TL;DR: A hybrid quantum mechanical/molecular mechanical (QM/MM) potential energy function with Hartree‐Fock, density functional theory (DFT), and post‐HF (RIMP2, MP2, CCSD) capability has been implemented in the CHARMM and Q‐Chem software packages.
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Restricted active space spin-flip configuration interaction approach: theory, implementation and examples.

TL;DR: The results suggest that the spin-flip method can provide a quite well balanced description of nearly degenerate electronic states at moderate computational cost.
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Inhibitive properties, thermodynamic and quantum chemical studies of alloxazine on mild steel corrosion in H2SO4

TL;DR: Alloxazine (ALLOX) was tested as corrosion inhibitor for mild steel in 0.5 M H 2 SO 4 solution using non-electrochemical technique (gravimetric and UV-visible spectrophotometric measurements) at 303-333 K as mentioned in this paper.
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.
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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