We describe an implementation of the cluster-in-molecule （CIM） resolution of the identity （RI） approximation second-order Moller-Plesset perturbation theory （CIM-RI-MP2）, with the purpose of extending RI-MP2 cal...We describe an implementation of the cluster-in-molecule （CIM） resolution of the identity （RI） approximation second-order Moller-Plesset perturbation theory （CIM-RI-MP2）, with the purpose of extending RI-MP2 calculations to very large systems. For typical conformers of several large polypeptides, we calculated their conformational energy differences with the CIM-RI-MP2 and the generalized energy-based fragmentation MP2 （GEBF-MP2） methods, and compared these results with the density functional theory （DFT） results obtained with several popular functionals. Our calculations show that the conformational energy differences obtained with CIM-RI-MP2 and GEBF-MP2 are very close to each other. In comparison with the GEBF-MP2 and CIM-RI-MP2 relative energies, we found that the DFT functionals （CAM-B3LYP-D3, LC-ωPBE-D3, M05-2X, M06-2X and coB97XD） can give quite accurate conformational energy differences for structurally similar conformers, but provide less-accurate results for structurally very different conformers.展开更多
基金supported by the National Natural Science Foundation of China(21073086,21333004)the National Basic Research Program of China(2011CB808501)
文摘We describe an implementation of the cluster-in-molecule （CIM） resolution of the identity （RI） approximation second-order Moller-Plesset perturbation theory （CIM-RI-MP2）, with the purpose of extending RI-MP2 calculations to very large systems. For typical conformers of several large polypeptides, we calculated their conformational energy differences with the CIM-RI-MP2 and the generalized energy-based fragmentation MP2 （GEBF-MP2） methods, and compared these results with the density functional theory （DFT） results obtained with several popular functionals. Our calculations show that the conformational energy differences obtained with CIM-RI-MP2 and GEBF-MP2 are very close to each other. In comparison with the GEBF-MP2 and CIM-RI-MP2 relative energies, we found that the DFT functionals （CAM-B3LYP-D3, LC-ωPBE-D3, M05-2X, M06-2X and coB97XD） can give quite accurate conformational energy differences for structurally similar conformers, but provide less-accurate results for structurally very different conformers.
