Volume 115, Issue 1, 01 July 2001
Index of content:
115(2001); http://dx.doi.org/10.1063/1.1381575View Description Hide Description
A high-resolution photoelectron spectrum of p-benzoquinone in the low energy (9.5–11.5 eV) region is reported and analyzed with the aid of simulations based on high-level ab initio calculations. The results generally support the notion that the two prominent spectral features in this region are each due to a pair of final ion states. The lower energy feature beginning near 10 eV is due to oxygen lone-pair ionizations, while that beginning near 11 eV comes from π electron removal. Contrary to previous interpretations of the spectrum, however, the results of this study indicate that the two π states are nearly degenerate, with the strongest peak in the photoelectron spectrum representing a convolution of the corresponding pair of 0–0 ionizations.
115(2001); http://dx.doi.org/10.1063/1.1383793View Description Hide Description
Instantaneous chirality induced by zero-point vibrations was observed directly by using the Coulomb explosion imaging (CEI) technique. The present results suggest the CEI would be generally applicable to diagnosis of the chirality of the isolated molecules in gas phase.
115(2001); http://dx.doi.org/10.1063/1.1383792View Description Hide Description
The reaction has been investigated using the universal crossed molecular beam method. A number of reaction pathways have been observed. One of the most interesting channels is the process, in which products are clearly identified. Experimental results indicate that the products are likely produced through a long-lived complex formation process, for which insertion of into the C–C bond should be responsible.
115(2001); http://dx.doi.org/10.1063/1.1383590View Description Hide Description
Molecular electronic ground-statetheories, whether ab initio, or semiempirical are most often formulated as a variational principle, where the electronic ground-state energy, considered a linear or nonlinear functional of a reduced density matrix, obtains a constrained minimum. In this communication, we present a Lagrangian analysis of the self-consistent-field electronic structure problem, which does not resort to the concept of orthogonal molecular orbitals. We also develop a method of constrained minimization efficiently applicable to nonlinear energy functional minimization, as well as to linear models such as tight-binding. The method is able to treat large molecules with an effort that scales linearly with the system size. It has built-in robustness and leads directly to the desired minimal solution. Performance is demonstrated on linear alkane and polyene chains.