Ab initio study of the C sub 3 sup + cation using multireference methods
Journal Article
·
· Journal of Physical Chemistry; (United States)
- ELORET Inst., Palo Alto, CA (United States)
- Limburgs Univ. Centrum (Belgium) Univ. of Antwerp, Wilrijk (Belgium)
- Limburgs Univ., Centrum (Belgium)
- Univ. of Antwerp, Wilrijk (Belgium)
The energy difference between the linear {sup 2}{Sigma}{sub u}{sup +} and cyclic {sup 2}B{sub 2} structures of C{sub 3}{sup +} has been investigated by using large (5s3p2dlf) basis sets and multireference electron correlation treatments, including complete active space SCF (CASSCF), multireference CI(MRCI), and averaged coupled-pair functional (ACPF) methods, as well as the single-reference quadratic configuration interaction (QCISD(T)) method. The authors best estimate, including a correction for basis set incompleteness, is that the linear form lies above the cyclic form by 5.2{sub {minus}1.0}{sup +1.5} kcal/mol. The {sup 2}{Sigma}{sub u}{sup +} state is probably not a transition state but a local minimum. Reliable computation of the cyclic/linear energy difference in C{sub 3}{sup +} is extremely demanding of the electron correlation treatment used: of the single-reference methods previously considered, CCSD(T) and QCISD(T) perform best. The MRCI+Q-(0.01)/(4s2pld) energy separation of 1.68 kcal/mol should provide a comparison standard for other electron correlation methods applied to this system.
- OSTI ID:
- 7017499
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:17; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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