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The Journal of Chemical Physics
Volumn 95, Issue 4, 1991, Pages 2623-2638
Coupled-cluster open-shell analytic gradients: Implementation of the direct product decomposition approach in energy gradient calculations
Author keywords

[No Author keywords available]
Indexed keywords

CLUSTER ANALYSIS; COMPUTATION THEORY; COMPUTER HARDWARE; DIGITAL ARITHMETIC; GRADIENT METHODS; MOLECULAR PHYSICS; NUMERICAL METHODS; SUPERCOMPUTERS;
EID: 36449002812     PISSN: 00219606     EISSN: None     Source Type: Journal    
DOI: 10.1063/1.460915     Document Type: Article
Times cited : (256)
References (70)
  • 28
  • 32
    • 84953816500 scopus 로고    scopus 로고
    • Fully factored equations have also been presented for the CCSDTQ model [see S. Kucharski and R. J. Bartlett (to be published)].
  • 33
    • 84953816499 scopus 로고    scopus 로고
    • The estimate given for the cycle time of a RHF calculation with 200 basis functions (20 occupied, 180 virtual orbitals) is based on the analysis of the computational cost of a CCSD calculation given in Ref. 35 and assumes an implementation running at the peak rate of 300 MFLOPS of a CRAY YMP. For the estimate of the total time of such a CCSD calculation, 15 iterations have been assumed and the timings for integral evaluation, SCF, and integral transformations have been extrapolated. No adjustments have been made for the extensive disk space and core memory requirements, so that our estimates correspond to a lower limit.
  • 46
    • 85034886615 scopus 로고    scopus 로고
    • ne term in the lambda equations may be written as ΛH¯, where H¯ is an effective Hamiltonian. Terms involving [formula omitted] and [formula omitted] vanish due to the satisfaction of the [formula omitted] and [formula omitted] amplitude equations. These terms were included in the equations presented diagrammatically in Ref. 16, but should be neglected in computational implementations.
  • 49
    • 84953816503 scopus 로고    scopus 로고
    • ACES n is a new quantum chemical program package especially designed for CC and MBPT energy and gradient calculations. Elements of this package are: the VMOL integral and VPROPS property integral programs written by P. R. Taylor and J. Almlof; SCF, integral transformation, correlation energy, and gradient codes written by J. F. Stanton, J. Gauss, J. D. Watts, W. J. Lauderdale, and R. J. Bartlett; a modified version of the integral derivative program ABACUS written by T. Helgaker, H. J. Aa. Jensen, P. Jo/rgensen, and P. R. Taylor; and a geometry optimization and vibrational analysis package written by J. F. Stanton and D. E. Bernholdt.
  • 54
    • 84953816466 scopus 로고    scopus 로고
    • The calculations have been carried out on a CRAY YMP/8–32 supercomputer with routines compiled with version 3.1.2.6. of the CFT77 compiler and the flowtrace option enabled.
  • 55
    • 84953816465 scopus 로고    scopus 로고
    • The timings for RHF-CC energy calculations given in the tables in this paper differ from those in Ref. 35, since a different algorithm is used to evaluate the particle-particle ladder [[formula omitted] operations] contraction in gradient calculations. In single point calculations, partial treatment of spin adaptation is employed, but has not yet been implemented for gradient calculations.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.