Propene dissociation channels were characterized by ab initio CCSD(T)/6-311++g(d,p) calculations. Inthis work the detailed mechanism of propene dissociation to C2H4+CH2, C2H2+H+CH3, C2H2+CH4 andC3H3+H2+H have been investigated. According to our calculations, ten fragments can be classified intofive dissociated channels. Our results point out that two mechanisms come into play in the H2 eliminat...

Equation of motion coupled-cluster singles and doubles (EOM-CCSD) is one of the most accurate computational methods for the description of one-electron vertical transitions. However, its O(N(6)) scaling, where N is the number of basis functions, often makes the study of molecules larger than 10-15 heavy atoms prohibitive. In this work we investigate how accurately less expensive methods can app...

An attempt is made to improve the currently accepted muonic value for the 197Au nuclear quadrupole moment [+0.547(16)x10(-28) m2] for the 3/2+ nuclear ground state obtained by Powers et al. [Nucl. Phys. A230, 413 (1974)]. From both measured Mossbauer electric quadrupole splittings and solid-state density-functional calculations for a large number of gold compounds a nuclear quadrupole moment of...

Krüger some years ago proposed a cluster LiBeBCNOF, now called periodane. His ground-state isomer proposal has recently been refined by Bera et al. using DFT. Here, we take the approach of molecules in such a cluster as starting point. We first study therefore the triangular molecule LiOB by coupled cluster theory (CCSD) and thereby specify accurately its equilibrium geometry in free space. The...

Coupled-cluster response theory for near-edge x-ray-absorption fine structure of atoms and molecules, 2012, Based on an asymmetric Lanczos-chain subspace algorithm, damped coupled cluster linear response functions have been implemented for the hierarchy of coupled cluster (CC) models including CC with single excitations (CCS), CC2, CC with single and double excitations (CCSD), and CCSD with non...

Recently, it has become possible to apply higher-order coupled-cluster methods to polyatomic systems including molecular noncovalent complexes. Due to the steep scaling of the complexity of these calculations, the size of the basis set becomes a critical factor and larger systems can be calculated only in small basis sets. To obtain the most accurate results, it is necessary to use composite sc...

Recent experiments on the UV and electron beam irradiation of solid O2 reveals a series of IR features near the valence antisymmetric vibration band of O3 which are frequently interpreted as the formation of unusual On allotropes in the forms of weak complexes or covalently bound molecules. In order to elucidate the question of the nature of the irradiation products, the structure, relative ene...

The equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) method has been implemented into the massively parallel ACES III program using two alternative strategies: (1) storing the entire EOM Hamiltonian matrix prior to diagonalization and (2) recomputing the four-virtual part of the matrix from integrals in a direct mode. The second is found to be far more efficient. EOM-CC shows v...

The potential energy surfaces of the ground electronic state of rare gas interhalogen van der Waals molecules, Rg–ICl ~Rg5He, Ne!, are calculated at CCSD~T! ~coupled cluster using single and double excitations with a noniterative perturbation treatment of triple excitations! level of theory. Calculations have been performed with specific augmented correlation consistent basis sets for the noble...