On the use of explicitly correlated treatment methods for the generation of accurate polyatomic -He/H-2 interaction potential energy surfaces: The case of C-3-He complex and generalization

Al Mogren, M. M.; Denis-Alpizar, O.; Ben Abdallah, D.; Stoecklin, T.; Halvick, P.; Senent, M-L; Hochlaf, M.

Abstract

Through the study of the C-3((X) over tilde (1)Sigma(+)(g)) + He(S-1) astrophysical relevant system using standard (CCSD(T)) and explicitly correlated (CCSD(T)-F12) coupled cluster approaches, we show that the CCSD(T)-F12/aug-cc-pVTZ level represents a good compromise between accuracy and low computational cost for the generation of multi-dimensional potential energy surfaces (PESs) over both intra- and inter-monomer degrees of freedom. Indeed, the CCSD(T)-F12/aug-cc-pVTZ 2D-PES for linear C-3 and the CCSD(T)-F12/aug-cc-pVTZ 4D-PES for bent C3 configurations gently approach those mapped at the CCSD(T)/aug-cc-pVXZ (X = T,Q) + bond functions level, whereas a strong reduction of computational effort is observed. After exact dynamical computations, the pattern of the rovibrational levels of the intermediate C-3-He complex and the rotational and rovibrational (de-) excitation of C-3 by He derived using both sets of PESs agree quite well. Since C-3 shows a floppy character, the interaction PES is defined in four dimensions to obtain realistic collisional parameters. The C-C-C bending mode, which fundamental lies at 63 cm(-1) and can be excited at very low temperatures is explicitly considered as independent coordinate. Our work suggests hence that CCSD(T)-F12/aug-cc-pVTZ methodology is the key method for the generation of accurate polyatomic - He/H-2 multi-dimensional PESs. (C) 2014 AIP Publishing LLC.

Más información

Título según WOS: ID WOS:000340712200045 Not found in local WOS DB
Título de la Revista: JOURNAL OF CHEMICAL PHYSICS
Volumen: 141
Número: 4
Editorial: AIP Publishing
Fecha de publicación: 2014
DOI:

10.1063/1.4890729

Notas: ISI