Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set

In the past, basis sets for use in correlated molecular calculations have largely been taken from single configuration calculations. Recently, Almlof, Taylor, and co‐workers have found that basis sets of natural orbitals derived from correlated atomic calculations (ANOs) provide an excellent description of molecular correlation effects. We report here a careful study of correlation effects in the oxygen atom, establishing that compact sets of primitive Gaussian functions effectively and efficiently describe correlation effects i f the exponents of the functions are optimized in atomic correlated calculations, although the primitive (s p) functions for describing correlation effects can be taken from atomic Hartree–Fock calculations i f the appropriate primitive set is used. Test calculations on oxygen‐containing molecules indicate that these primitive basis sets describe molecular correlation effects as well as the ANO sets of Almlof and Taylor. Guided by the calculations on oxygen, basis sets for use in correlated atomic and molecular calculations were developed for all of the first row atoms from boron through neon and for hydrogen. As in the oxygen atom calculations, it was found that the incremental energy lowerings due to the addition of correlating functions fall into distinct groups. This leads to the concept of c o r r e l a t i o n c o n s i s t e n t b a s i s s e t s, i.e., sets which include all functions in a given group as well as all functions in any higher groups. Correlation consistent sets are given for all of the atoms considered. The most accurate sets determined in this way, [5s4p3d2f1g], consistently yield 99% of the correlation energy obtained with the corresponding ANO sets, even though the latter contains 50% more primitive functions and twice as many primitive polarization functions. It is estimated that this set yields 94%–97% of the total (HF+1+2) correlation energy for the atoms neon through boron.

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

We present two new hybrid meta exchange- correlation functionals, called M06 and M06-2X. The M06 functional is parametrized including both transition metals and nonmetals, whereas the M06-2X functional is a high-nonlocality functional with double the amount of nonlocal exchange (2X), and it is parametrized only for nonmetals.The functionals, along with the previously published M06-L local functional and the M06-HF full-Hartree–Fock functionals, constitute the M06 suite of complementary functionals. We assess these four functionals by comparing their performance to that of 12 other functionals and Hartree–Fock theory for 403 energetic data in 29 diverse databases, including ten databases for thermochemistry, four databases for kinetics, eight databases for noncovalent interactions, three databases for transition metal bonding, one database for metal atom excitation energies, and three databases for molecular excitation energies. We also illustrate the performance of these 17 methods for three databases containing 40 bond lengths and for databases containing 38 vibrational frequencies and 15 vibrational zero point energies. We recommend the M06-2X functional for applications involving main-group thermochemistry, kinetics, noncovalent interactions, and electronic excitation energies to valence and Rydberg states. We recommend the M06 functional for application in organometallic and inorganometallic chemistry and for noncovalent interactions.

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The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细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用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

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

A description of the ab initio quantum chemistry package GAMESS is presented. Chemical systems containing atoms through radon 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. Emphasis is given to novel features of the program. The parallelization strategy used in the RHF, ROHF, UHF, and GVB sections of the program is described, and detailed speecup results are given. Parallel calculations can be run on ordinary workstations as well as dedicated parallel machines. © John Wiley & Sons, Inc.

General atomic and molecular electronic structure system

The C 1s and O 1s ionization energies are calculated for formaldehyde, acetaldehyde, and acetone, and the calculated results are compared to the experimental X-ray photoelectron spectra. The theoretical techniques employed involve the ΔSCF method followed by a perturbative CI treatment to capture electron correlation effects. The calculated C 1s and O 1s ionization energies including electron correlation are within ∼0.5 eV of the experimental values

A Theoretical Study of the X‐Ray Photoelectron Ionization Energies of Related Carbonyl Compounds: Formaldehyde, Acetaldehyde, and Acetone.

Zero‐field splittings were calculated for benzene, pyridine, and a number of simple derivatives. The experimental decrease of the zfs parameter D upon addition of substituents on the benzene and pyridine rings and upon protonation of pyridine was reproduced theoretically without invoking either aplanarity or nπ* interaction. For a lowest ππ* triplet state of pyridine, D = 0.165 cm−1 and E = −0.020 cm−1 are predicted. Zfs integrals were calculated from a wave function formed from CNDO/2 orbitals with two‐configuration CI, using a five‐term Gaussian expansion with the best Slater exponents for atoms in molecules.

Calculations of zero-field splittings in pyridine derivatives

Some aspects of the triplet di-π-methane rearrangement: comparison of the ring opening of cyclopropyldicarbinyl and cyclopropylcarbinyl

Theoretical Investigation of Several Low‐Lying States of trans,trans‐1,3,5‐Hexatriene

This critical review highlights intricacies of the computational study of the Cope rearrangement of 1,5-hexadiene and its derivatives. It is demonstrated that a realistic potential energy surface in the transition region can be obtained only at very high levels of approximation. The emphasis is on the reasons why some generally reliable methods fail to make even qualitatively correct predictions about this reaction.

Ernest R. Davidson

Papers

A Theoretical Study of the X‐Ray Photoelectron Ionization Energies of Related Carbonyl Compounds: Formaldehyde, Acetaldehyde, and Acetone.

Calculations of zero-field splittings in pyridine derivatives

Some aspects of the triplet di-π-methane rearrangement: comparison of the ring opening of cyclopropyldicarbinyl and cyclopropylcarbinyl

Theoretical Investigation of Several Low‐Lying States of trans,trans‐1,3,5‐Hexatriene

The Cope Rearrangement in Theoretical Retrospect