ZIB

Treffer pro Seite

Treffer 1 - 4 | 4 Treffer

Sortierung

Digitale Medien

Orbital-invariant second-order many-body perturbation theory on parallel computers: An approach for large molecules (1995)

Bernholdt, David E. ; Harrison, Robert J.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 102 (1995), S. 9582-9589

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The equations for the second-order many-body perturbation theory [MBPT(2)] energy are derived in an orbital-invariant representation, analogous to that obtained with the method of self-consistent electron pairs of Meyer. This formulation is well suited to take advantage of the localized nature of interactions in large chemical systems in order to reduce the computational effort required to study them. This formulation of the MBPT(2) method also lends itself to implementation on parallel computers. We describe a scalable implementation in which the key data are distributed across the parallel computer rather than being replicated. Portability to both shared- and distributed-memory computer architectures is provided through the use of a subroutine library implementing a "global array'' programming model. We demonstrate that this approach is scalable even for relatively small chemical systems.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.468774

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

Digitale Medien

The structure and binding energy of K+–ether complexes: A comparison of MP2, RI-MP2, and density functional methods (1996)

Feller, David ; Aprà, Edoardo ; Nichols, Jeff A. ; [weitere]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 105 (1996), S. 1940-1950

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The structures and binding energies of several cation:ether complexes (K+:dimethyl ether, K+:dimethoxyethane, K+:12-crown-4 and K+:18-crown-6) were determined with second and fourth order perturbation theory using correlation consistent basis sets. Several of these are the largest correlated calculations yet attempted on crown ethers. The observed systematic convergence to the complete basis set limit provides a standard by which the accuracy of previous studies can be measured and facilitates the calibration of density functional methods. Recent Fouier transform ion cyclotron resonance experiments predicted K+:18-crown-6 binding energies which were significantly smaller than ab initio calculations. None of the potential sources of error examined in the present study were large enough to explain this difference. Although the 6-31+G* basis set used in an earlier theoretical study was smaller than the smallest of the correlation consistent basis sets, with suitable correction for basis set superposition error, it appears capable of yielding binding energies within several kcal/mol of the basis set limit. Perturbation theory calculations exploiting the "resolution of the identity'' approximation were found to faithfully reproduce binding energies and conformational differences. Although the cation–ether interaction is dominated by classical electrostatics, the accuracy of density functional techniques was found to be quite sensitive to the choice of functionals. The local density SVWN procedure performed well for binding energies and conformational differences, while underestimating K+O distances by up to 0.08 A(ring). The gradient-corrected Becke–Lee–Yang–Parr functional underestimated the K+:12c4 binding energy by 4–7 kcal/mol or 15%. © 1996 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.472082

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

Digitale Medien

Fitting basis sets for the RI-MP2 approximate second-order many-body perturbation theory method (1998)

Bernholdt, David E.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 109 (1998), S. 1593-1600

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The "resolution of the identity" integral approximation applied to second-order many-body perturbation theory, or RI-MP2, method offers improved computational performance compared to traditional (exact) second-order perturbation theory calculations, but introduces a new auxiliary or "fitting basis set" into the method. We develop fitting basis sets for use with the correlation consistent cc-pVDZ and cc-pVTZ atomic orbital basis sets for the atoms H-Ne. These fitting sets are designed to reproduce exact second-order results for a set of 32 test cases, including a variety of reaction energies, weak interactions, and electrostatic properties, to better than 1% error averaged across all tests and less than 2% error in any individual case. Although the RI-MP2 method is primarily targeted to large-scale calculations, it offers substantial performance improvements even for the small molecules used in these test cases. © 1998 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.476732

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

Digitale Medien

Toward high-performance computational chemistry: II. A scalable self-consistent field program (1996)

Harrison, Robert J. ; Guest, Martyn F. ; Kendall, Rick A. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Computational Chemistry 17 (1996), S. 124-132

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0192-8651

Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Informatik

Notizen: We discuss issues in developing scalable parallel algorithms and focus on the distribution, as opposed to the replication, of key data structures. Replication of large data structures limits the maximum calculation size by imposing a low ratio of processors to memory. Only applications which distribute both data and computation across processors are truly scalable. The use of shared data structures that may be independently accessed by each process even in a distributed memory environment greatly simplifies development and provides a significant performance enhancement. We describe tools we have developed to support this programming paradigm. These tools are used to develop a highly efficient and scalable algorithm to perform self-consistent field calculations on molecular systems. A simple and classical strip-mining algorithm suffices to achieve an efficient and scalable Fock matrix construction in which all matrices are fully distributed. By strip mining over atoms, we also exploit all available sparsity and pave the way to adopting more sophisticated methods for summation of the Coulomb and exchange interactions. © 1996 by John Wiley & Sons, Inc.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Treffer 1 - 4 | 4 Treffer