Search results for "moment"
showing 10 items of 3027 documents
Theoretical study of electronically excited cis- and trans-glyoxal
1997
Abstract The equation-of-motion coupled cluster method for excitation energies in the singles and doubles approximation (EOMEE-CCSD) is applied to an investigation of the structure and harmonic frequencies of planar conformers of glyoxal in their first excited singlet states. For the trans-isomer, agreement between calculated harmonic frequencies and observed fundamentals is generally satisfactory, although the theoretical values are slightly more than 10% too high for the carbonyl stretching modes. Parallel calculations of the corresponding ground state properties allow for an empirical prediction of the excited state frequencies in which calculated differences in normal-mode frequencies a…
Full configuration interaction calculation of BeH adiabatic states.
2008
An all-electron full configuration interaction (FCI) calculation of the adiabatic potential energy curves of some of the lower states of BeH molecule is presented. A moderately large ANO basis set of atomic natural orbitals (ANO) augmented with Rydberg functions has been used in order to describe the valence and Rydberg states and their interactions. The Rydberg set of ANOs has been placed on the Be at all bond distances. So, the basis set can be described as 4s3p2d1f3s2p1d(BeH)+4s4p2d(Be). The dipole moments of several states and transition dipole strengths from the ground state are also reported as a function of the R(Be-H) distance. The position and the number of states involved in sever…
Molecular Stark-effect spectroscopy of Prodan and Laurdan in different solvents and electric dipole moments in their equilibrated ground and Franck–C…
2007
Abstract The results from electrooptical absorption measurements (EOAM) on the ground and excited Franck–Condon state dipole moments of Prodan and Laurdan in 1,4-dioxane and cyclohexane are presented. The ground and excited Franck–Condon state electric dipole moments as well as the respective transition moment of both probes are parallel. The electric dipole moments of Prodan and Laurdan in the ground state in cyclohexane and 1,4-dioxane have values within the range (15.7–16.5) × 10 −30 C m. On optical excitation the dipole moments increase by (42.1–49.5) × 10 −30 C m. The obtained results are compared with the values of the dipole moments of Prodan and Laurdan determined by other methods.
Studies of rotational level Λ-doubling by rf-optical double resonance spectroscopy: application to NaK D1Π
1997
Abstract We report here the application of optical-radio frequency double resonance spectroscopy for individual rotational levels of the NaK D 1 Π state. Lambda doubling constant q values for five ν′, J ′ levels are obtained. These data are combined with measurements of dc e - f Stark-mixing-induced changes in optical spectra, and the electric dipole moment d p in the D 1 Π state is determined.
Quantum dynamical study of the O(1D) + CH4→ CH3+ OH atmospheric reaction
2014
Time independent quantum mechanical (TIQM) scattering calculations have been carried out for the O((1)D) + CH4(X(1)A1) → CH3(X(2)A2″) + OH(X(2)Π) atmospheric reaction, using an ab initio ground potential energy surface where the CH3 group is described as a pseudo-atom. Total and state-to-state reaction probabilities for a total angular momentum J = 0 have been determined for collision energies up to 0.5 eV. The vibrational and rotational state OH product distributions show no specific behavior. The rate coefficient has been calculated by means of the J-shifting approach in the 10-500 K temperature range and slightly depends on T at ordinary temperatures (as expected for a barrierless reacti…
Vibrational analysis of the electronic spectrum of ethylene based onab initio SCF-CI calculations
1972
Ab initio calculations for CH2 twisting and CC stretching vibrational wavefunctions and energy levels are reported for various electronic states of ethylene C2H4. Electronic transition moments between these states are also obtained to allow a calculation of the oscillator strengths for vibrational transitions involved in various electronic band systems; from this study it is concluded that thevertical electronic energy differenceΔE e may differ significantly from the energy of the absorption maximumΔE max with which it is often equated. In particular it is found in the case of theπ→π * singlet-singlet excitation of ethylene that theΔE e value overestimates the most probable vibrational tran…
Nonlinear chiral transport in Dirac semimetals
2018
We study the current of chiral charge density in a Dirac semimetal with two Dirac points in momentum space, subjected to an externally applied time dependent electric field and in the presence of a magnetic field. Based on the kinetic equation approach, we find contributions to the chiral charge current, that are proportional to the second power of the electric field and to the first and second powers of the magnetic field, describing the interplay of the chiral anomaly and the drift motion of electrons moving under the action of electric and magnetic fields.
Forward doubly-virtual Compton scattering off the nucleon in chiral perturbation theory: The subtraction function and moments of unpolarized structur…
2020
The forward doubly-virtual Compton scattering (VVCS) off the nucleon contains a wealth of information on nucleon structure, relevant to the calculation of the two-photon-exchange effects in atomic spectroscopy and electron scattering. We report on a complete next-to-leading-order (NLO) calculation of low-energy VVCS in chiral perturbation theory ($\chi$PT). Here we focus on the unpolarized VVCS amplitudes $T_1(\nu, Q^2)$ and $T_2(\nu, Q^2)$, and the corresponding structure functions $F_1(x, Q^2)$ and $F_2(x,Q^2)$. Our results are confronted, where possible, with "data-driven" dispersive evaluations of low-energy structure quantities, such as nucleon polarizabilities. We find significant dis…
Investigations of Chl a aggregates cross-linked by dioxane in 3-methylpentane
1997
In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Q -region absorption spectrum of the y chlorophyll a-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 and 702 nm. The emission spectrum consists of two emission bands centred at 699 and 702 nm suggesting the presence of two types of aggregates. High degree of fluorescence polarization is detected yielding the angles between the absorption transition moments with respect to the 702 nm emission transition moment. The …
Identification of stiffness, dissipation and input parameters of multi degree of freedom civil systems under unmeasured base excitations
2009
A time domain dynamic identification technique based on a statistical moment approach has been formulated for civil systems under base random excitations in the linear state. This technique is based on the use of classically damped models characterized by a mass proportional damping. By applying the Itô stochastic calculus, special algebraic equations that depend on the statistical moments of the response can be obtained. These equations can be used for the dynamic identification of the mechanical parameters that define the structural model, in the case of unmeasured input as well, and the identification of the input itself. Furthermore, the above equations demonstrate the possibility of id…