A MRCC study of the isomerisation of cyclopropane. (17th November 2017)

• Record Type: Journal Article
• Authors: Lang, Jakub; Švaňa, Matej; Demel, Ondřej; Brabec, Jiri; Kedžuch, Stanislav; Noga, Jozef; Kowalski, Karol; Pittner, Jiří
• Is Part Of: Molecular physics. Volume 115:Number 21/22(2017)
• Page Start: 2743
• Page End: 2754
• Publication Date: 2017-11-17
• Subjects: Coupled cluster -- LPNO, trimethylene -- universal state selective -- multireference; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2017.1317112
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: Mukherjee's and Brillouin-Wigner multi-reference coupled cluster methods with universal state selective (USS) corrections were used to study the isomerisation of cyclopropane to propene through a trimethylene/propylidene diradicals. Main aim was to obtain high quality ab-initio data using advanced methods that treat both static and dynamic correlation in the involved species, however, we also report implementation of the diagonal USS correction in the LPNO-MRCC code and its performance assessment. The MkCCSD(T)/cc-pV5Z lower bound of interaction energy of cyclopropane isomerisation via trimethylene is 65.6 kcal/mol (59.9 kcal/mol with ZPVE correction), in a good agreement with experimental values in the range 60–65 kcal/mol. The MkCCSD(T)/cc-pV5Z adiabatic singlet-triplet gap in trimethylene is 0.6 kcal/mol, slightly higher than previous CASPT2 result −0.7 kcal/mol by Skancke et al. Abstract :