Search results for "Molecular configuration"
showing 8 items of 8 documents
A theory ofnonverticaltriplet energy transfer in terms of accurate potential energy surfaces: The transfer reaction from π,π* triplet donors to 1,3,5…
2004
Triplet energy transfer (TET) from aromatic donors to 1,3,5,7-cyclooctatetraene (COT) is an extreme case of "nonvertical" behavior, where the transfer rate for low-energy donors is considerably faster than that predicted for a thermally activated (Arrhenius) process. To explain the anomalous TET of COT and other molecules, a new theoretical model based on transition state theory for nonadiabatic processes is proposed here, which makes use of the adiabatic potential energy surfaces (PES) of reactants and products, as computed from high-level quantum mechanical methods, and a nonadiabatic transfer rate constant. It is shown that the rate of transfer depends on a geometrical distortion paramet…
Full configuration interaction calculation of singlet excited states of Be3
2004
The full configuration interaction (FCI) study of the singlets vertical spectrum of the neutral beryllium trimer has been performed using atomic natural orbitals [3s2p1d] basis set. The FCI triangular equilibrium structure of the ground state has been used to calculate the FCI vertical excitation energies up to 4.8 eV. The FCI vertical ionization potential for the same geometry and basis set amounts to 7.6292 eV. The FCI dipole and quadrupole transition moments from the ground state are reported as well. The FCI electric quadrupole moment of the X (3)A(1) (') ground state has been also calculated with the same basis set (Theta(zz)=-2.6461 a.u., Theta(xx)=Theta(yy)=-1/2Theta(zz)). Twelve of …
Magic numbers, excitation levels, and other properties of small neutral math clusters (N < 50)
2006
The ground-state energies and the radial and pair distribution functions of neutral math clusters are systematically calculated by the diffusion Monte Carlo method in steps of one math atom from 3 to 50 atoms. In addition the chemical potential and the low-lying excitation levels of each cluster are determined with high precision. These calculations reveal that the “magic numbers” observed in experimental math cluster size distributions, measured for free jet gas expansions by nondestructive matter-wave diffraction, are not caused by enhanced stabilities. Instead they are explained in terms of an enhanced growth due to sharp peaks in the equilibrium concentrations in the early part of the e…
Excited states of the water molecule: Analysis of the valence and Rydberg character
2008
The excited states of the water molecule have been analyzed by using the extended quantum-chemical multistate CASPT2 method, namely, MS-CASPT2, in conjunction with large one-electron basis sets of atomic natural orbital type. The study includes 13 singlet and triplet excited states, both valence and 3s-, 3p-, and 3d-members of the Rydberg series converging to the lowest ionization potential and the 3s- and 3p-Rydberg members converging to the second low-lying state of the cation, 1 math. The research has been focused on the analysis of the valence or Rydberg character of the low-lying states. The computation of the 1 math state of water at different geometries indicates that it has a predom…
Lower Rydberg series of methane: a combined coupled cluster linear response and molecular quantum defect orbital calculation.
2006
Vertical excitation energies as well as related absolute photoabsorption oscillator strength data are very scarce in the literature for methane. In this study, we have characterized the three existing series of low-lying Rydberg states of CH4 by computing coupled cluster linear response (CCLR) vertical excitation energies together with oscillator strengths in the molecular-adapted quantum defect orbital formalism from a distorted Cs geometry selected on the basis of outer valence green function calculations. The present work provides a wide range of data of excitation energies and absolute oscillator strengths which correspond to the Rydberg series converging to the three lower ionization p…
Antikaon-nucleon interaction and Lambda(1405) in chiral SU(3) dynamics
2016
The properties of the Lambda(1405) resonance are key ingredients for determining the antikaon-nucleon interaction in strangeness nuclear physics, and the novel internal structure of the Lambda(1405) is of great interest in hadron physics, as a prototype case of a baryon that does not fit into the simple three-quark picture. We show that a quantitative description of the antikaon-nucleon interaction with the Lambda(1405) is achieved in the framework of chiral SU(3) dynamics, with the help of recent experimental progress. Further constraints on the Kbar N subthreshold interaction are provided by analyzing pi Sigma spectra in various processes, such as the K-d -> pi Sigma n reaction and the…
Crystal structure determination of 1-pentanol from low-temperature powder diffraction data by Patterson search methods
2005
5 pages.-- PACS: 61.66.Hq; 61.50.Lt
The role of dislocations in the solid-state polymerization of monomers having conjugated triple bonds: A study of 2,4-hexadiyne-1,6-diol bis(p-toluen…
1975
The crystal structure of the monomer bis(p-toluene sulfonate) ester of 2,4-hexadiyne-1,6-diol (pT) is conducive from the viewpoint of both the separation distances and molecular configuration, to polymerization, irrespective of whether initiation is thermal, photochemical, or mechanical. The dislocations present in the monomer and polymer structures have been characterized by employing optical microscopic techniques. The slip system (102)[010] is found to be present in both monomer and polymer crystals but the (010)[001] system is found only in the monomer. On this basis a crystal structure for the monomer is proposed based on existing crystallographic information relating to the structure …