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 effect of unitary transformations among the occupied orbitals of the beryllium atom is discussed. It is shown that pair‐pair interaction energies become large for choices other than the canonical Roothaan‐Hartree‐Fock orbitals. The many‐body perturbation theory diagrams responsible for these effects are discussed.

Unitary Transformations and Pair Energies. III. Relation to Perturbation Theory

Ab initio configuration interaction (CI) calculations have been carried out in order to determine the energy difference between 3A i2 trimethylenemethane (TMM) and 1Ag butadiene. The pi CI value of 38.3 kcal/mol is very similar to the CI values obtained when excitations of the sigma electrons are permitted. This finding suggests that correlation effects involving sigma orbitals make at most a small contribution to the energy differences between non-Kekule hydrocarbon diradicals and their closed-shell isomers. Possible complications in the experimental measurement of this energy difference are discussed. It is pointed out that methylenecyclopropane might be formed in attempts to deprotonate the 2-methallyl cation, without the involvement of TMM. From the experimental heats of formation of methylenecyclopropane and butadiene, an energy difference of 14–16 kcal/mol between 3A i2 TMM and methylenecyclopropane is estimated. This is in excellent agreement with a previous energy difference obtained by direct calculation.

Ab Initio CI Calculations of the Energy Difference between Trimethylenemethane and Butadiene

The performance of commonly used correlation and exchange-correlation functionals has been studied for highly charged atomic ions. Calculated energies have been compared with exact nonrelativistic energies of atomic species with 2–18 electrons for nuclei from Z 2 He to Z 26 Ni . It is found that all density functionals considered here reveal problems in the description of correlation effects as a function of nuclear charge Z. S1050-2947 98 09309-3

Ground-state energies of isoelectronic atomic series from density-functional theory : exploring the accuracy of density functionals

Multi-reference perturbation theory

The S 1 ( 1 B 2u )-S 0 ( 1 A g ) spectroscopy of p-difluorobenzene-d 4 (C 6 D 4 F 2 , pDFB-d 4 ) cooled in a supersonic free jet expansion has been characterized by fluorescence excitation (FE) and dispersed fluorescence. The O 0 0 band lies at 36 987±1.0 cm -1 (vacuum). The FE band assignments have provided the values of 11 S 1 fundamentals. The pattern of Franck-Condon allowed vibrational activity and of vibronically induced transitions is similar to that of pDFB-h 4

Ernest R. Davidson

Papers

Unitary Transformations and Pair Energies. III. Relation to Perturbation Theory

Ab Initio CI Calculations of the Energy Difference between Trimethylenemethane and Butadiene

Ground-state energies of isoelectronic atomic series from density-functional theory : exploring the accuracy of density functionals

Multi-reference perturbation theory

Vibrations of S1 (1B2u) p-difluorobenzene-d4 S1-S0 fluorescence spectroscopy and ab initio calculations