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31st IEEE International Parallel and Distributed Processing Symposium Workshops (IPDPS)

作者： Shan, Hongzhang Williams, Samuel Johnson, Calvin McElvain, Kenneth Lawrence Berkeley Natl Lab Computat Res Div Berkeley CA 94720 USA San Diego State Univ Dept Phys San Diego CA 92182 USA Univ Calif Berkeley Dept Phys Berkeley CA 94720 USA

ISBN: (纸本)9780769561493

The configuration interaction (CI) method has been widely used to solve the non-relativistic many-body Schrodinger equation. One great challenge to implementing it efficiently on manycore architectures is its immense memory and data movement requirements. To address this issue, within each node, we exploit a hybrid MPI+OpenMP programming model in lieu of the traditional flat MPI programming model. In this paper, we develop optimizations that partition the workloads among OpenMP threads based on data locality, which is essential in ensuring applications with complex data access patterns scale well on manycore architectures. The new algorithm scales to 256 threads on the 64-core Intel Knights Landing (KNL) manycore processor and 24 threads on dual-socket Ivy Bridge (Xeon) nodes. Compared with the original implementation, the performance has been improved by up to 7x on the Knights Landing processor and 3x on the dual-socket Ivy Bridge node.

关键词： bigstick configuration-interaction method hybrid programming model Ivy bridge knights landing locality-based threading algorithm Manycore MPI multithreading OpenMP

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Singly and doubly excited states of butadiene, acrolein, and glyoxal: Geometries and electronic spectra

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JOURNAL OF CHEMICAL PHYSICS 2006年第1期125卷 14316-1-14316-页

作者： Saha, Biswajit Ehara, Masahiro Nakatsuji, Hiroshi Kyoto Univ Grad Sch Engn Dept Synthet Chem & Biol Chem Nishikyo Ku Kyoto 6158510 Japan Kyoto Univ Fukui Inst Fundamental Chem Sakyo Ku Kyoto 6068103 Japan

Excited-state geometries and electronic spectra of butadiene, acrolein, and glyoxal have been investigated by the symmetry adapted cluster configuration interaction (SAC-CI) method in their s-trans conformation. Valence and Rydberg states below the ionization threshold have been precisely calculated with sufficiently flexible basis sets. Vertical and adiabatic excitation energies were well reproduced and the detailed assignments were given taking account of the second moments. The deviations of the vertical excitation energies from the experiment were less than 0.3 eV for all cases. The SAC-CI geometry optimization has been applied to some valence and Rydberg excited states of these molecules in the planar structure. The optimized ground- and excited-state geometries agree well with the available experimental values;deviations lie within 0.03 A and 0.7 degrees for the bond lengths and angles, respectively. The force acting on the nuclei caused by the excitations has been discussed in detail by calculating the SAC-CI electron density difference between the ground and excited states;the geometry relaxation was well interpreted with the electrostatic force theory. In Rydberg excitations, geometry changes were also noticed. Doubly excited states (so-called 2 (1)A(g) states) were investigated by the SAC-CI general-R method considering up to quadruple excitations. The characteristic geometrical changes and large energetic relaxations were predicted for these states.

关键词： SYMMETRY-ADAPTED-CLUSTER configuration-interaction method ANALYTICAL ENERGYGRADIENT GENERAL-R method SAC CI THEORIES N-PI-ASTERISK RYDBERG EXCITATIONS TRANS-BUTADIENE TRIPLET-STATES WAVE-FUNCTION

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Relativistic Calculations of the Chemical Properties of the Superheavy Element with Z=119 and Its Homologues

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OPTICS AND SPECTROSCOPY 2021年第9期129卷 1038-1044页

作者： Tupitsyn, I. I. Malyshev, A. V. Glazov, D. A. Kaygorodov, M. Y. Kozhedub, Y. S. Savelyev, I. M. Shabaev, V. M. St Petersburg State Univ St Petersburg 199034 Russia

Relativistic calculations of the electronic structure of the superheavy element of the eighth period-eka-francium (Z = 119) and its homologues, which form the group of alkali metals, are performed in the framework of the configuration-interaction method and many-body perturbation theory using the basis of the Dirac-Fock-Sturm orbitals (DFS). The obtained values of the ionization potentials, electron affinities, and root-mean-square radii are compared with the corresponding values calculated within the nonrelativistic approximation. A comparison with the available experimental data and the results of previous theoretical calculations is given as well. The analysis of the obtained results indicates a significant influence of the relativistic effects for the francium and eka-francium atoms, which leads to a violation of the monotonic behaviour of the listed above chemical properties as a function of the alkaline-element atomic number. In addition, the quantum electrodynamics corrections to the ionization potentials are evaluated by employing the model Lamb-shift operator (QEDMOD).

关键词： superheavy elements alkali metals relativistic effects correlation effects quantum electrodynamics corrections configuration-interaction method ionization potentials electron affinities

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Role of the electric dipole moment in positron binding to the ground and excited states of the BeO molecule

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JOURNAL OF CHEMICAL PHYSICS 2007年第10期126卷 4305-1-4305-7页

作者： Buenker, Robert J. Liebermann, Heinz-Peter Pichl, Lukas Tachikawa, Masanori Kimura, Mineo Berg Univ Wuppertal Fachbereich Math & Nat Wissensch C D-42119 Wuppertal Germany Int Christian Univ Div Nat Sci Mitaka Tokyo 1818585 Japan Yokohama City Univ Grad Sch Integrated Sci Quantum Chem Div Yokohama Kanagawa 2360027 Japan Kyushu Univ Grad Sch Sci Fukuoka 8158611 Japan

Self-consistent-field and multireference single- and double-excitation configuration interaction (CI) calculations have been carried out for various electronic states of the beryllium oxide molecule and their positron-attached counterparts. Particular emphasis is placed on the correlation between the polarity of a given BeO state and the magnitude of the positron binding energy as the internuclear distance is varied. Potential curves are computed for all BeO states that correlate with the first three atomic limits for this system and good agreement is found between the experimental and calculated spectroscopic constants in all cases. The present level of CI treatment is known to underestimate the positron affinities of atoms by at least several tenths of an eV, and this fact needs to be taken into account in evaluating the results for positron binding to molecules. The lowest BeO excited states ((3,1)Pi) are not found to bind with a positron in the Franck-Condon region due to their comparatively small dipole moments caused by O to Be charge transfer relative to the X (1)Sigma(+) ground state, which in turn does have a fairly sizeable positron affinity. The situation changes significantly as dissociation proceeds, however, with both (4,2)Pi and (2)Sigma(+) positronic states lying several tenths of an eV lower than their neutral counterparts over a broad range of internuclear distance.

关键词： configuration-interaction method ALKALI HYDRIDES COMPLEXES CI SYSTEMS ATOMS

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Correlation energy extrapolation by intrinsic scaling. III. Compact wave functions

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JOURNAL OF CHEMICAL PHYSICS 2004年第22期121卷 10852-10862页

作者： Bytautas, L Ruedenberg, K Iowa State Univ Dept Chem Ames IA 50011 USA Iowa State Univ US DOE Ames Lab Ames IA 50011 USA

The information gained in the context of extrapolating the correlation energy by intrinsic scaling is used to shorten the full configurational expansions of electronic wave function without compromising their chemical accuracy. The truncations are accomplished by judiciously limiting the participation of the ranges of predetermined approximate sets of natural orbitals in the various excitation categories. (C) 2004 American Institute of Physics.

关键词： REDUCED DENSITY-MATRICES configuration-interaction method MOLECULARELECTRONIC-STRUCTURE DETERMINING QUANTUM ENERGIES CORRECT ASYMPTOTIC-BEHAVIOR CONSISTENT-FIELDmethod MULTIPLE ACTIVE SPACES SCHRODINGER-EQUATION EXACT-EXCHANGE VARIABLE OCCUPATIONS

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Correlation energy extrapolation by intrinsic scaling. I. method and application to the neon atom

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JOURNAL OF CHEMICAL PHYSICS 2004年第22期121卷 10905-10918页

作者： Bytautas, L Ruedenberg, K Iowa State Univ Dept Chem Ames IA 50011 USA Iowa State Univ US DOE Ames Lab Ames IA 50011 USA

Remarkably accurate scaling relations are shown to exist between the correlation energy contributions from various excitation levels of the configuration interaction approach, considered as functions of the size of the correlating orbital space. These relationships are used to develop a method for extrapolating a sequence of smaller configuration interaction calculations to the full configuration-interaction energy. Calculations of the neon atom ground state with the Dunning's quadruple zeta basis set demonstrate the ability of the method to obtain benchmark quality results. (C) 2004 American Institute of Physics.

关键词： PLESSET PERTURBATION-THEORY configuration-interaction method COUPLED-CLUSTER THEORY MATRIX RENORMALIZATION-GROUP EXACT WAVE-FUNCTION ELECTRONICSCHRODINGER-EQUATION CONSISTENT-FIELD method MULTIPLE ACTIVE SPACES GAUSSIAN-BASIS SETS QUANTUM-CHEMISTRY

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High-order excitations in state-universal and state-specific multireference coupled cluster theories: Model systems

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JOURNAL OF CHEMICAL PHYSICS 2006年第15期125卷 54113-1-54113-页

作者： Evangelista, Francesco A. Allen, Wesley D. Schaefer, Henry F., III Univ Georgia Ctr Computat Chem Athens GA 30602 USA

For the first time high-order excitations (n>2) have been studied in three multireference couple cluster (MRCC) theories built on the wave operator formalism: (1) the state-universal (SU) method of Jeziorski and Monkhorst (JM) (2) the state-specific Brillouin-Wigner (BW) coupled cluster method, and (3) the state-specific MRCC approach of Mukherjee (Mk). For the H4, P4, BeH2, and H8 models, multireference coupled cluster wave functions, with complete excitations ranging from doubles to hextuples, have been computed with a new arbitrary-order string-based code. Comparison is then made to corresponding single-reference coupled cluster and full configuration interaction (FCI) results. For the ground states the BW and Mk methods are found, in general, to provide more accurate results than the SU approach at all levels of truncation of the cluster operator. The inclusion of connected triple excitations reduces the nonparallelism error in singles and doubles MRCC energies by a factor of 2-10. In the BeH2 and H8 models, the inclusion of all quadruple excitations yields absolute energies within 1 kcal mol(-1) of the FCI limit. While the MRCC methods are very effective in multireference regions of the potential energy surfaces, they are outperformed by single-reference CC when one electronic configuration dominates. (c) 2006 American Institute of Physics.

关键词： configuration-interaction method POTENTIAL-ENERGY SURFACES BODYPERTURBATION THEORIES EXCITED ELECTRONIC STATES QUASI-DEGENERATE STATES SINGLE-ROOT APPROACH N-2TRIPLE BOND BRILLOUIN-WIGNER REDUCED MULTIREFERENCE OPEN-SHELL

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CVRQD ab initio ground-state adiabatic potential energy surfaces for the water molecule

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JOURNAL OF CHEMICAL PHYSICS 2006年第20期125卷 4307-1-4307-1页

作者： Barletta, Paolo Shirin, Sergei V. Zobov, Nikolai F. Polyansky, Oleg L. Tennyson, Jonathan Valeev, Edward F. Csaszar, Attila G. UCL Dept Phys & Astron London WC1E 6BT England Eotvos Lorand Univ Inst Chem Lab Mol Spect H-1518 Budapest Hungary Russian Acad Sci Inst Phys Appl Nizhnii Novgorod 603950 Russia Virginia Tech Dept Chem Blacksburg VA 24061 USA Eotvos Lorand Univ Inst Chem Lab Mol Spect H-1518 Budapest Hungary

The high accuracy ab initio adiabatic potential energy surfaces (PESs) of the ground electronic state of the water molecule, determined originally by Polyansky [Science 299, 539 (2003)] and called CVRQD, are extended and carefully characterized and analyzed. The CVRQD potential energy surfaces are obtained from extrapolation to the complete basis set of nearly full configuration interaction valence-only electronic structure computations, augmented by core, relativistic, quantum electrodynamics, and diagonal Born-Oppenheimer corrections. We also report ab initio calculations of several quantities characterizing the CVRQD PESs, including equilibrium and vibrationally averaged (0 K) structures, harmonic and anharmonic force fields, harmonic vibrational frequencies, vibrational fundamentals, and zero-point energies. They can be considered as the best ab initio estimates of these quantities available today. Results of first-principles computations on the rovibrational energy levels of several isotopologues of the water molecule are also presented, based on the CVRQD PESs and the use of variational nuclear motion calculations employing an exact kinetic energy operator given in orthogonal internal coordinates. The variational nuclear motion calculations also include a simplified treatment of nonadiabatic effects. This sophisticated procedure to compute rovibrational energy levels reproduces all the known rovibrational levels of the water isotopologues considered, (H2O)-O-16, (H2O)-O-17, (H2O)-O-18, and (D2O)-O-16, to better than 1 cm(-1) on average. Finally, prospects for further improvement of the ground-state adiabatic ab initio PESs of water are discussed. (c) 2006 American Institute of Physics.

关键词： VIBRATION-ROTATION LEVELS BORN-OPPENHEIMER APPROXIMATION configuration-interaction method SIZE-EXTENSIVE MODIFICATION BASIS-SET CONVERGENCE COUPLED-CLUSTER RELATIVISTIC CORRECTIONS TRANSITION FREQUENCIES WAVE-FUNCTIONS LIMIT

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State-specific multireference complete-active-space coupled-cluster approach versus other quantum chemical methods:: dissociation of the N₂ molecule

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MOLECULAR PHYSICS 2007年第10期105卷 1335-1357页

作者： Lyakh, Dmitry I. Ivanov, Vladimir V. Adamowicz, Ludwik Univ Arizona Dept Chem Tucson AZ 85721 USA Kharkov Natl Univ Dept Chem Kharkov Ukraine

A comprehensive comparison of different quantum-chemical methods applied to calculate the N-2 ground state potential energy curve is presented. In the comparison we highlight the multireference state-specific (MRSS) coupled- cluster (CC) approach with the complete-activespace (CAS) reference and with single and double excitations from all reference determinants in the CC operator developed in our group. The method is called CASCCSD. The energy and amplitude equations for the method and the corresponding computer code have been generated using a computerized automative procedure that in the present work was extended to produce a parallel computer code. The complete CASCCSD wave function for N-2 includes some selected eight-fold excitations in the CC operator. An analysis of the wave function estimates the importance of those excitations at large internuclear separations.

关键词： SINGLE-REFERENCE FORMALISM POTENTIAL-ENERGY SURFACES configuration-interaction method MATRIX RENORMALIZATION-GROUP ELECTRONIC-STRUCTURE methodS BODYPERTURBATION-THEORY GAUSSIAN BASIS FUNCTIONS ATOMIC BASIS SETS FIRST-ROW ATOMS EXCITED-STATES

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On the ultraviolet photodissociation of H₂Te

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JOURNAL OF CHEMICAL PHYSICS 2004年第19期121卷 9389-9395页

作者： Alekseyev, AB Liebermann, HP Wittig, C Berg Univ Gesamthsch Wuppertal Fachbereich C Theoret Chem D-42097 Wuppertal Germany Univ So Calif Dept Chem Los Angeles CA 90089 USA

The photodissociation of H2Te through excitation in the first absorption band is investigated by means of multireference spin-orbit configuration interaction (CI) calculations. Bending potentials for low-lying electronic states of H2Te are obtained in C-2v symmetry for Te-H distances fixed at the ground state equilibrium value of 3.14a(0), as well as for the minimum energy path constrained to R-1=R-2. Asymmetric cuts of potential energy surfaces for excited states (at R-1=3.14a(0) and theta=90.3degrees) are obtained for the first time. It is shown that vibrational structure in the 380-400 nm region of the long wavelength absorption tail is due to transitions to 3A('), which has a shallow minimum at large HTe-H separations. Transitions to this state are polarized in the molecular plane, and this state converges to the excited TeH((2)Pi(1/2))+H(S-2) limit. These theoretical data are in accord with the selectivity toward TeH((2)Pi(1/2)) relative to TeH((2)Pi(3/2)) that has been found experimentally for 355 nm H2Te photodissociation. The calculated 3A'<--(X) over tildeA' transition dipole moment increases rapidly with HTe-H distance;this explains the observation of 3A(') vibrational structure for low vibrational levels, despite unfavorable Franck-Condon factors. According to the calculated vertical energies and transition moment data, the maximum in the first absorption band at approximate to245 nm is caused by excitation to 4A", which has predominantly 2(1)A(") (B-1(1) in C-2v symmetry) character. (C) 2004 American Institute of Physics.

关键词： configuration-interaction method POTENTIAL-ENERGY SURFACES HYDROGENTELLURIDE ELECTRONIC STATES CI CALCULATIONS HIGH-RESOLUTION H2S BANDS PHOTOABSORPTION EXTRAPOLATION

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