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Title: DMRG-CASPT2 study of the longitudinal static second hyperpolarizability of all-trans polyenes

Abstract

We have implemented internally contracted complete active space second order perturbation theory (CASPT2) with the density matrix renormalization group (DMRG) as active space solver [Y. Kurashige and T. Yanai, J. Chem. Phys. 135, 094104 (2011)]. Internally contracted CASPT2 requires to contract the generalized Fock matrix with the 4-particle reduced density matrix (4-RDM) of the reference wavefunction. The required 4-RDM elements can be obtained from 3-particle reduced density matrices (3-RDM) of different wavefunctions, formed by symmetry-conserving single-particle excitations op top of the reference wavefunction. In our spin-adapted DMRG code CHEMPS2https://github.com/sebwouters/chemps2, we decompose these excited wavefunctions as spin-adapted matrix product states and calculate their 3-RDM in order to obtain the required contraction of the generalized Fock matrix with the 4-RDM of the reference wavefunction. In this work, we study the longitudinal static second hyperpolarizability of all-trans polyenes C{sub 2n}H{sub 2n+2} [n = 4–12] in the cc-pVDZ basis set. DMRG-SCF and DMRG-CASPT2 yield substantially lower values and scaling with system size compared to RHF and MP2, respectively.

Authors:
; ;  [1]
  1. Center for Molecular Modelling, Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium)
Publication Date:
OSTI Identifier:
22678969
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 145; Journal Issue: 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DENSITY MATRIX; PERTURBATION THEORY; POLYENES; WAVE FUNCTIONS

Citation Formats

Wouters, Sebastian, Van Speybroeck, Veronique, and Van Neck, Dimitri. DMRG-CASPT2 study of the longitudinal static second hyperpolarizability of all-trans polyenes. United States: N. p., 2016. Web. doi:10.1063/1.4959817.
Wouters, Sebastian, Van Speybroeck, Veronique, & Van Neck, Dimitri. DMRG-CASPT2 study of the longitudinal static second hyperpolarizability of all-trans polyenes. United States. doi:10.1063/1.4959817.
Wouters, Sebastian, Van Speybroeck, Veronique, and Van Neck, Dimitri. Sun . "DMRG-CASPT2 study of the longitudinal static second hyperpolarizability of all-trans polyenes". United States. doi:10.1063/1.4959817.
@article{osti_22678969,
title = {DMRG-CASPT2 study of the longitudinal static second hyperpolarizability of all-trans polyenes},
author = {Wouters, Sebastian and Van Speybroeck, Veronique and Van Neck, Dimitri},
abstractNote = {We have implemented internally contracted complete active space second order perturbation theory (CASPT2) with the density matrix renormalization group (DMRG) as active space solver [Y. Kurashige and T. Yanai, J. Chem. Phys. 135, 094104 (2011)]. Internally contracted CASPT2 requires to contract the generalized Fock matrix with the 4-particle reduced density matrix (4-RDM) of the reference wavefunction. The required 4-RDM elements can be obtained from 3-particle reduced density matrices (3-RDM) of different wavefunctions, formed by symmetry-conserving single-particle excitations op top of the reference wavefunction. In our spin-adapted DMRG code CHEMPS2https://github.com/sebwouters/chemps2, we decompose these excited wavefunctions as spin-adapted matrix product states and calculate their 3-RDM in order to obtain the required contraction of the generalized Fock matrix with the 4-RDM of the reference wavefunction. In this work, we study the longitudinal static second hyperpolarizability of all-trans polyenes C{sub 2n}H{sub 2n+2} [n = 4–12] in the cc-pVDZ basis set. DMRG-SCF and DMRG-CASPT2 yield substantially lower values and scaling with system size compared to RHF and MP2, respectively.},
doi = {10.1063/1.4959817},
journal = {Journal of Chemical Physics},
number = 5,
volume = 145,
place = {United States},
year = {Sun Aug 07 00:00:00 EDT 2016},
month = {Sun Aug 07 00:00:00 EDT 2016}
}