Vibrational state controlled bond cleavage in the photodissociation of isocyanic acid (HNCO)
We report the bond selected photodissociation of isocyanic acid (HNCO). This molecule dissociates from its first excited singlet state, breaking either the N–H bond to form H+NCO (X 2) or the C&...
We report the bond selected photodissociation of isocyanic acid (HNCO). This molecule dissociates from its first excited singlet state, breaking either the N–H bond to form H+NCO (X 2) or the C&...
Direct calculation of overtones: Application to the CD3H molecule
We report a comparison of two methods designed for directly determining high lying energy levels in a polyatomic molecule. The Bloch operator, in the distorted wave version proposed by Jolicard [Chem....
We report a comparison of two methods designed for directly determining high lying energy levels in a polyatomic molecule. The Bloch operator, in the distorted wave version proposed by Jolicard [Chem....
A quantitative study of the scaling properties of the Hartree–Fock method
J. Chem. Phys. 102, 8448 (1995); doi:10.1063/1.468836
Issue Date: 1 June 1995
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Although it is usually stated that the Hartree–Fock method formally scales as N4, where N is the number of basis functions employed in the calculation, it is also well known that mathematical bounds computed with the Schwarz inequality can be used to screen and eliminate four-center two-electron integrals smaller than a certain threshold. In this work, quantitative data is presented to illustrate the effects of this integral screening on the scaling properties of the Hartree–Fock (HF) method. Calculations are performed on a range of carbon–hydrogen model systems, two-dimensional graphitic sheets, and three-dimensional diamond pieces, to determine the effective scaling exponent 
of the computational expense. The data obtained in this paper for calculations including over 250 carbon atoms and 1500 basis functions shows two significant trends: (1) in the asymptotic limit of large molecules, is found to be approximately 2.2–2.3, and (2) for molecules of modest size, is still very much less than 4. Therefore, integral screening is quantitatively shown to substantially reduce the Hartree–Fock scaling from its formal value of N4. ©1995 American Institute of Physics.
of the computational expense. The data obtained in this paper for calculations including over 250 carbon atoms and 1500 basis functions shows two significant trends: (1) in the asymptotic limit of large molecules, is found to be approximately 2.2–2.3, and (2) for molecules of modest size, is still very much less than 4. Therefore, integral screening is quantitatively shown to substantially reduce the Hartree–Fock scaling from its formal value of N4. ©1995 American Institute of Physics.
| History: | Received 20 December 1994; accepted 28 February 1995 |
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http://link.aip.org/link/?JCPSA6/102/8448/1 |
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KEYWORDS and PACS
- 31.15.Ne
Electronic structure of atoms, molecules and their ions: theory Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations) Self-consistent-field methods - YEAR: 1995
PUBLICATION DATA
0021-9606 (print)
1089-7690 (online)
AIP
REFERENCES (12)
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