Multistate Complete-Active-Space Second-Order Perturbation Theory Based on Density Matrix Renormalization Group Reference States
Abstract
We present the development of the multistate multireference second-order perturbation theory (CASPT2) with multiroot references, which are described using the density matrix renormalization group (DMRG) method to handle a large active space. The multistate first-order wave functions are expanded into the internally contracted (IC) basis of the single-state single-reference (SS-SR) scheme, which is shown to be the most feasible variant to use DMRG references. The feasibility of the SS-SR scheme comes from two factors: first, it formally does not require the fourth-order transition reduced density matrix (TRDM) and second, the computational complexity scales linearly with the number of the reference states. The extended multistate (XMS) treatment is further incorporated, giving suited treatment of the zeroth-order Hamiltonian despite the fact that the SS-SR based IC basis is not invariant with respect to the XMS rotation. In addition, the state-specific fourth-order reduced density matrix (RDM) is eliminated in an approximate fashion using the cumulant reconstruction formula, as also done in the previous state-specific DMRG-cu(4)-CASPT2 approach. The resultant method, referred to as DMRG-cu(4)-XMS-CASPT2, uses the RDMs and TRDMs of up to third-order provided by the DMRG calculation. The multistate potential energy curves of the photoisomerization of diarylethene derivatives with CAS(26e,24o) are presented to illustrate the applicability of our theoretical approach.
Additional Information
© 2017 American Chemical Society. This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: July 10, 2017; Published: September 7, 2017. This work was supported partially by JSPS KAKENHI Grant Nos. JP15H01097, JP16H04101, and JP17H05274 for T.Y. and National Natural Science Foundation of China (21501189) and Grant-in-Aid for Invitational Fellowship for Research in Japan (L16525) for X.-G.X. J.Ch. was supported by the Grant Agency of the Czech Republic (Grant No. 15-19143S) and institutional support RVO 61388963 (CAS). The authors declare no competing financial interest.Attached Files
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Supplemental Material - ct7b00735_si_003.xyz
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Additional details
- Eprint ID
- 81441
- Resolver ID
- CaltechAUTHORS:20170914-110138411
- JP15H01097
- Japan Society for the Promotion of Science (JSPS)
- JP16H04101
- Japan Society for the Promotion of Science (JSPS)
- JP17H05274
- Japan Society for the Promotion of Science (JSPS)
- 21501189
- National Natural Science Foundation of China
- L16525
- Japan Society for the Promotion of Science (JSPS)
- 15-19143S
- Grant Agency of the Czech Republic
- RVO 61388963
- Grant Agency of the Czech Republic
- Created
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2017-09-14Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field