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Title: First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results

Abstract

First principle calculations of effective exchange integrals (J) in the Heisenberg model for diradical species were performed by both symmetry-adapted (SA) multi-reference (MR) and broken-symmetry (BS) single reference (SR) methods. Mukherjee-type (Mk) state specific (SS) MR coupled-cluster (CC) calculations by the use of natural orbital (NO) references of ROHF, UHF, UDFT and CASSCF solutions were carried out to elucidate J values for di- and poly-radical species. Spin-unrestricted Hartree Fock (UHF) based coupled-cluster (CC) computations were also performed to these species. Comparison between UHF-NO(UNO)-MkMRCC and BS UHF-CC computational results indicated that spin-contamination of UHF-CC solutions still remains at the SD level. In order to eliminate the spin contamination, approximate spin-projection (AP) scheme was applied for UCC, and the AP procedure indeed corrected the error to yield good agreement with MkMRCC in energy. The CC double with spin-unrestricted Brueckner's orbital (UBD) was furthermore employed for these species, showing that spin-contamination involved in UHF solutions is largely suppressed, and therefore AP scheme for UBCCD removed easily the rest of spin-contamination. We also performed spin-unrestricted pure- and hybrid-density functional theory (UDFT) calculations of diradical and polyradical species. Three different computational schemes for total spin angular momentums were examined for the AP correction of themore » hybrid (H) UDFT. HUDFT calculations followed by AP, HUDFT(AP), yielded the S-T gaps that were qualitatively in good agreement with those of MkMRCCSD, UHF-CC(AP) and UB-CC(AP). Thus a systematic comparison among MkMRCCSD, UCC(AP) UBD(AP) and UDFT(AP) was performed concerning with the first principle calculations of J values in di- and poly-radical species. It was found that BS (AP) methods reproduce MkMRCCSD results, indicating their applicability to large exchange coupled systems.« less

Authors:
 [1]; ; ; ; ; ; ; ;  [2]
  1. Institute for Nano Science Design Center, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and TOYOTA Physical and Chemical Research Institute, Nagakute, Aichi, 480-1192 (Japan)
  2. Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan)
Publication Date:
OSTI Identifier:
22390877
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1642; Journal Issue: 1; Conference: ICCMSE-2010: International Conference of Computational Methods in Sciences and Engineering 2010, Kos (Greece), 3-8 Oct 2010; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPARATIVE EVALUATIONS; CORRECTIONS; DENSITY FUNCTIONAL METHOD; ERRORS; HARTREE-FOCK METHOD; HEISENBERG MODEL; INTEGRALS; MATHEMATICAL SOLUTIONS; NITRIC OXIDE; SYMMETRY BREAKING

Citation Formats

Yamaguchi, Kizashi, Nishihara, Satomichi, Saito, Toru, Yamanaka, Shusuke, Kitagawa, Yasutaka, Kawakami, Takashi, Yamada, Satoru, Isobe, Hiroshi, and Okumura, Mitsutaka. First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results. United States: N. p., 2015. Web. doi:10.1063/1.4906626.
Yamaguchi, Kizashi, Nishihara, Satomichi, Saito, Toru, Yamanaka, Shusuke, Kitagawa, Yasutaka, Kawakami, Takashi, Yamada, Satoru, Isobe, Hiroshi, & Okumura, Mitsutaka. First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results. United States. doi:10.1063/1.4906626.
Yamaguchi, Kizashi, Nishihara, Satomichi, Saito, Toru, Yamanaka, Shusuke, Kitagawa, Yasutaka, Kawakami, Takashi, Yamada, Satoru, Isobe, Hiroshi, and Okumura, Mitsutaka. Thu . "First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results". United States. doi:10.1063/1.4906626.
@article{osti_22390877,
title = {First principle calculations of effective exchange integrals: Comparison between SR (BS) and MR computational results},
author = {Yamaguchi, Kizashi and Nishihara, Satomichi and Saito, Toru and Yamanaka, Shusuke and Kitagawa, Yasutaka and Kawakami, Takashi and Yamada, Satoru and Isobe, Hiroshi and Okumura, Mitsutaka},
abstractNote = {First principle calculations of effective exchange integrals (J) in the Heisenberg model for diradical species were performed by both symmetry-adapted (SA) multi-reference (MR) and broken-symmetry (BS) single reference (SR) methods. Mukherjee-type (Mk) state specific (SS) MR coupled-cluster (CC) calculations by the use of natural orbital (NO) references of ROHF, UHF, UDFT and CASSCF solutions were carried out to elucidate J values for di- and poly-radical species. Spin-unrestricted Hartree Fock (UHF) based coupled-cluster (CC) computations were also performed to these species. Comparison between UHF-NO(UNO)-MkMRCC and BS UHF-CC computational results indicated that spin-contamination of UHF-CC solutions still remains at the SD level. In order to eliminate the spin contamination, approximate spin-projection (AP) scheme was applied for UCC, and the AP procedure indeed corrected the error to yield good agreement with MkMRCC in energy. The CC double with spin-unrestricted Brueckner's orbital (UBD) was furthermore employed for these species, showing that spin-contamination involved in UHF solutions is largely suppressed, and therefore AP scheme for UBCCD removed easily the rest of spin-contamination. We also performed spin-unrestricted pure- and hybrid-density functional theory (UDFT) calculations of diradical and polyradical species. Three different computational schemes for total spin angular momentums were examined for the AP correction of the hybrid (H) UDFT. HUDFT calculations followed by AP, HUDFT(AP), yielded the S-T gaps that were qualitatively in good agreement with those of MkMRCCSD, UHF-CC(AP) and UB-CC(AP). Thus a systematic comparison among MkMRCCSD, UCC(AP) UBD(AP) and UDFT(AP) was performed concerning with the first principle calculations of J values in di- and poly-radical species. It was found that BS (AP) methods reproduce MkMRCCSD results, indicating their applicability to large exchange coupled systems.},
doi = {10.1063/1.4906626},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1642,
place = {United States},
year = {Thu Jan 22 00:00:00 EST 2015},
month = {Thu Jan 22 00:00:00 EST 2015}
}