MkMRCC, APUCC, APUBD calculations of didehydronated species: comparison among calculated through-bond effective exchange integrals for diradicals

Mukherjee's type of multireference coupled-cluster (MkMRCC), approximate spin-projected spin-unrestricted CC (APUCC), and AP spin-unrestricted Brueckner's (APUBD) methods were applied to didehydronated ethylene, allyl cation, cis-butadiene, and naphthalene. The focus is on descriptions of...

Full description

Saved in:
Bibliographic Details
Published in:Molecular physics 2010-10, Vol.108 (19-20), p.2533-2541
Main Authors: Saito, Toru, Nishihara, Satomichi, Yamanaka, Shusuke, Kitagawa, Yasutaka, Kawakami, Takashi, Okumura, Mitsutaka, Yamaguchi, Kizashi
Format: Article
Language:English
Subjects:
approximate spin-projection coupled-cluster
Cations
Correlation
didehydronated species
Ethylene
hybrid density functional theory
Magnetic properties
Mathematical analysis
Molecular physics
multireference coupled-cluster
Naphthalene
Orbitals
radical systems
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Mukherjee's type of multireference coupled-cluster (MkMRCC), approximate spin-projected spin-unrestricted CC (APUCC), and AP spin-unrestricted Brueckner's (APUBD) methods were applied to didehydronated ethylene, allyl cation, cis-butadiene, and naphthalene. The focus is on descriptions of magnetic properties for these diradical species such as S-T gaps and diradical characters. Several types of orbital sets were examined as reference orbitals for MkMRCC calculations, and it was found that the change of orbital sets do not give significant impacts on computational results for these species. Comparison of MkMRCC results with APUCC and APUBD results show that these two types of methods yield similar results. These results show that the quantum spin corrected UCC and UBD methods can effectively account for both nondynamical and dynamical correlation effects that are covered by the MkMRCC methods. It was also shown that appropriately parameterized hybrid density functional theory (DFT) with AP corrections (APUDFT) calculations yielded very accurate data that qualitatively agree with those of MRCC and APUBD methods. This hierarchy of methods, MRCC, APUCC, and APUDFT, is expected to constitute a series of standard ab initio approaches towards radical systems, among which we could choose one of them, depending on the size of the systems and the required accuracy.
ISSN:0026-8976
1362-3028
DOI:10.1080/00268976.2010.508755