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Ernest R. Davidson

Other affiliations: Lawrence Livermore National Laboratory, Indiana University, IBM  ...read more
Bio: Ernest R. Davidson is an academic researcher from University of Washington. The author has contributed to research in topics: Configuration interaction & Ab initio. The author has an hindex of 78, co-authored 480 publications receiving 30616 citations. Previous affiliations of Ernest R. Davidson include Lawrence Livermore National Laboratory & Indiana University.


Papers
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Book ChapterDOI
01 Jan 1983
TL;DR: Efficiency must be judged in terms of the ability to solve a variety of eigenvalue problems on computers of widely different architecture, memory size, and data transfer rates.
Abstract: Widespread use of the linear variation method in quantum mechanics leads to the need for efficient matrix eigenvalue methods for real symmetric matrices. Efficiency must be judged, however, in terms of the ability to solve a variety of eigenvalue problems on computers of widely different architecture, memory size, and data transfer rates. To further confuse the situation, cost rather than system throughput, is usually of paramount concern. Additionally, algorithms vary widely in ease of programming, simplicity, reliability, portability and availability as part of standard packages. Consequently there are a wide variety of eigenvalue algorithms in use, and a typical quantum laboratory will incorporate several of these into their program package.

103 citations

Journal ArticleDOI
TL;DR: In this article, the exact high-Z limit for atomic ions with up to 18 electrons was determined using degenerate second-order perturbation theory for the correlation contribution to the energies of atomic ion with 3−18 electrons.
Abstract: Davidson and co-workers (Phys. Rev. A 1991, 44, 7071; 1993, 47, 3649) have estimated the nonrelativistic correlation energies and relativistic corrections to ionization potentials for atomic ions with up to 18 electrons. However, due to the lack of theoretical values for the high-Z limits and lack of more accurate compilations of experimental ionization potentials, the analysis for 11−18 electrons required further investigation. In this work, we have accurately determined the exact high-Z limit employing degenerate second order perturbation theory for the correlation contribution to the energies of atomic ions with 3−18 electrons. We have also incorporated the experimental compilation of the electron affinity data of Hotop and Lineberger for the low-Z limit. This high-Z limit is compared with the results of the LYP correlation energy functional. The LYP correlation functional is also compared with the correlation energy of electrons in an external harmonic potential of infinite force constant.

102 citations

Journal ArticleDOI
TL;DR: In this article, zero kinetic energy electron spectra of aniline were recorded and a number of ion vibrational frequencies accurately measured and the adiabatic ionization potential was found to be 62.271±2 cm−1.
Abstract: Zero kinetic energy electron spectra of aniline are recorded and a number of ion vibrational frequencies accurately measured. The adiabatic ionization potential of aniline is found to be 62 271±2 cm−1. Ab initio calculations provide insights into the bonding changes that take place in aniline upon ionization. Reasonable agreement between calculated and measured frequencies in the ground states of aniline neutral and ion is obtained.

101 citations

Journal ArticleDOI
TL;DR: The Kolos and Roothaan wave function for H2 has been analyzed into natural orbitals and it was found that the first natural orbital is nearly the SCF function as mentioned in this paper.
Abstract: The Kolos and Roothaan wavefunction for H2 has been analyzed into natural orbitals. It was found that the first natural orbital is nearly the SCF function. The first four natural orbitals provide a good description of the molecule and give a total energy of —1.169884 hartrees. Beyond the first four terms, the natural expansion becomes more slowly convergent.

100 citations


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Journal ArticleDOI
TL;DR: A detailed description and comparison of algorithms for performing ab-initio quantum-mechanical calculations using pseudopotentials and a plane-wave basis set is presented in this article. But this is not a comparison of our algorithm with the one presented in this paper.

47,666 citations

Journal ArticleDOI
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.
Abstract: 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.

26,705 citations

Journal ArticleDOI
TL;DR: The M06-2X meta-exchange correlation function is proposed in this paper, which is parametrized including both transition metals and nonmetals, and is a high-non-locality functional with double the amount of nonlocal exchange.
Abstract: 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.

22,326 citations

28 Jul 2005
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.
Abstract: 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。

18,940 citations

Journal ArticleDOI
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.
Abstract: 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.

18,546 citations