Structures and Transition States of Ge2CH2.

In this study a systematic theoreticalinvestigation of Ge2CH2is carried out. Thesinglet potential energysurface (PES) was explored using state-of-the-art theoretical methodsincluding self-consistent field (SCF), coupled cluster theory incorporatingsingle and double excitation (CCSD), perturbative triple [CCSD(T)]and full triples [CCSDT] with perturbative quadruple (Q), togetherwith a variety of correlation-consistent polarized valence basis setscc-pVXZ (where X = D, T, and Q). A total of eleven stationary pointshave been located on the Ge2CH2singlet groundstate PES. Among them, seven structures are minima (1S–7S), two are transition states (TS1and TS2), and two are second-order saddle points (SSP1and SSP2). The global minimum is predictedto be an exotic hydrogen-bridged structure 1S. The energyordering of the seven minima (in kcal mol–1) obtainedfrom focal point analysis using the extrapolation to complete basisset (CBS) limit with zero point vibrational energy (ZPVE), core correlation,diagonal Born–Oppenheimer (DBOC) and relativistic correctionis 1S[0.0] < 2S[17.2] < 3S[18.3] < 4S[31.7] < 5S[39.9] < 6S[58.1] < 7S[82.1]. [ABSTRACT FROM AUTHOR]