The optimized molecular structures, harmonic vibrational wavenumbers, and corresponding vibrational assignments of 2-, 3and 4-cyanopyridines have been calculated using Gaussian 03 set of quantum chemistry code. Calculations were carried out at Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) level using the standard 6-311++G(d,p)basis set. The geometrical parameters, thermodynamic ...

The methodology for a vibrational analysis within the nuclear–electronic orbital ~NEO! framework is presented. In the NEO approach, specified nuclei are treated quantum mechanically on the same level as the electrons, and mixed nuclear–electronic wave functions are calculated variationally with molecular orbital methods. Both electronic and nuclear molecular orbitals are expressed as linear com...

Highly accurate quantum-mechanical calculations az presented for highly excited vibrational states of HzO. The vibration Hamiltonian operator Hvib for a nonlinear triatomic molecule is given in Radau coordinates. A direct product basis is chosen, and the Hvib matrix is evaluated in the discrete variable representation (DVR) for the symmetrized Radau coordinates. Vibrational eigenstates are comp...

Vibrational level structure in the S(0) (1)A(g) and S(1) (1)B(3u) states of pyrene was investigated through analysis of fluorescence excitation spectra and dispersed fluorescence spectra for single vibronic level excitation in a supersonic jet and through referring to the results of ab initio theoretical calculation. The vibrational energies are very similar in the both states. We found broad s...

The conformational stability and vibrational infrared and Raman spectra of trichloroacetyl isocyanate (CCl3CONCO) were investigated by ab initio MP2 and density functional B3LYP calculations using the 6-311++G** basis set. From the potential energy scans of the internal rotations in both the halomethyl and the isocyanate rotors, the molecule was predicted to exist predominantly in the cis-cis c...

The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9<or=v(")<or=21 and 1<or=J(")<or=14 were assigned to the X (1)Sigma(+) state of NaH. The highest vibrational level ob...

We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C6H5OH). The measurements were carried out at incident electron energies in the range 15-40 eV and for scattered-electron angles in the range 10-90°. The energy resolution of those measurements was ty...

We present a crossed beam study of the title reaction over the collision energy range from 0.47 to 1.20 eV, over which the dynamics of particle transfer are direct. The data include vibrational state populations and vibrational-state dependent angular distributions. Over the entire collision energy range, the product vibrational state distributions are inverted, and the extent of that inversion...

Electronic and vibrational structures in the S(0) (1)A(1) and S(1) (1)A(1) states of jet-cooled phenanthrene-h(10) and phenanthrene-d(10) were analyzed by high-resolution spectroscopy using a tunable nanosecond pulsed laser. The normal vibrational energies and molecular structures were estimated by ab initio calculations with geometry optimization in order to carry out a normal-mode analysis of...

The complete vibrational spectrum of the HO2(X(2)A' ') radical, up to the H + O2 dissociation limit, has been determined quantum mechanically on an accurate potential energy surface (PES), based on approximately 15000 ab initio points at the icMRCI+Q/aug-cc-pVQZ level of theory. The vibrational states are found to be assignable at low energies but become more irregular as the energy approaches ...