Accuracy of the three-body fragment molecular orbital method applied to Moller-Plesset perturbation theory
by Fedorov, D. G.; Ishimura, K.; Ishida, T.; Kitaura, K.; Pulay, P.; Nagase, S.
The three-body energy expansion in the fragment molecular orbital method (FMO) was applied to the 2nd order Moller-Plesset theory (MP2). The accuracy of both the two and three-body expansions was determined for water clusters, alanine n-mers (alpha-helices and beta-strands) and one synthetic protein, using the 6-31G* and 6-311G* basis sets. At the best level of theory (three-body, two molecules/residues per fragment), the absolute errors in energy relative to ab initio MP2 were at most 1.2 and 5.0 mhartree, for the 6-31G* and 6-311G* basis sets, respectively. The relative accuracy was at worst 99.996% and 99.96%, for 6-31G* and 6-311G*, respectively. A three-body approximation was introduced and the optimum threshold value was determined. The protein calculation (6-31G*) at the production level (FMO2/2) took 3 h on 36 3.2-GHz Pentium 4 nodes and had the absolute error in the MP2 correlation energy of only 2 kcal/mol.
- Journal
- Journal of Computational Chemistry
- Volume
- 28
- Issue
- 9
- Year
- 2007
- Start Page
- 1476-1484
- URL
- https://dx.doi.org/10.1002/jcc.20645
- ISBN/ISSN
- 1096-987X; 0192-8651
- DOI
- 10.1002/jcc.20645