A parallel vectorized implementation of triple excitations in CCSD(T): application to the binding energies of the AlH3, AlH2F, AlHF2 and AlF3 dimers
✍ Scribed by Alistair P. Rendell; Timothy J. Lee; Andrew Komornicki
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 812 KB
- Volume
- 178
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
An efficient method for evaluating various non-iterative estimates of connected triple excitations in coupled-cluster theory is outlined and related to a similar expression occurring in Meller-Plesset perturbation theory. The method is highly vectorized and capable of utilizing multiple processors on a shared-memory machine, leading to computational rates in excess of one billion floating-point operations per second on four processors of a CRAY Y-MP. Using the new procedure, the binding energies of the DZh diborane-type dimers of AlH3, AlH2F, AlHF* and AIF> have been determined to be 32,40,20 and 47 kcal/mol, respectively. For A&Fe, the correlation procedure includes 232 molecular orbital5 and over I .5 x IO6 single and double coupled-cluster amplitudes, effectively accounting for over 2 x 1 O9 connected triple excitations.