On the use of explicitly correlated treatment methods for the generation of accurate polyatomic -He/H2 interaction potential energy surfaces: The case of C3-He complex and generalization
Through the study of the C3(X̃1Σ g +) + He(1S) 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 ge...
| Autores: | , , , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2014 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/110599 |
| Acesso em linha: | http://hdl.handle.net/10261/110599 |
| Access Level: | acceso abierto |
| Palavra-chave: | Bound states Manifolds Potential energy surfaces Excited states Coupled cluster |
| Resumo: | Through the study of the C3(X̃1Σ g +) + He(1S) 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 C3 and the CCSD(T)-F12/aug-cc-pVTZ 4D-PES for bent C 3 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 C3-He complex and the rotational and rovibrational (de-) excitation of C3 by He derived using both sets of PESs agree quite well. Since C3 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/H2 multi-dimensional PESs. © 2014 AIP Publishing LLC. |
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