Results 1 - 10 of 134535
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[en] The efficiency of materials developed for solar energy and technological applications depends on the interplay between molecular architecture and light-induced electronic energy redistribution. The spatial localization of electronic excitations is very sensitive to molecular distortions. Vibrational nuclear motions can couple to electronic dynamics driving changes in localization. The electronic energy transfer among multiple chromophores arises from several distinct mechanisms that can give rise to experimentally measured signals. Atomistic simulations of coupled electron-vibrational dynamics can help uncover the nuclear motions directing energy flow. Through careful analysis of excited state wave function evolution and a useful fragmenting of multichromophore systems, through-bond transport and exciton hopping (through-space) mechanisms can be distinguished. Such insights are crucial in the interpretation of fluorescence anisotropy measurements and can aid materials design. Finally, this Perspective highlights the interconnected vibrational and electronic motions at the foundation of nonadiabatic dynamics where nuclear motions, including torsional rotations and bond vibrations, drive electronic transitions.
[en] The potential energy curve (PEC) of HI(X1Σ+) molecule is studied using the complete active space self-consistent field method followed by the highly accurate valence internally contracted multireference configuration interaction approach at the correlation-consistent basis sets, aug-cc-pV6Z for H and aug-cc-pV5Z-pp for I atom. Using the PEC of HI(X1Σ+), the spectroscopic parameters of three isotopes, HI(X1Σ+), DI(X1Σ+) and TI(X1Σ+), are determined in the present work. For the HI(X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are 3.1551 eV, 3.2958 eV, 0.16183 nm, 2290.60 cm−1, 40.0703 cm−1, 0.1699 cm−1 and 6.4373 cm−1, respectively; for the DI (X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are 3.1965 eV, 3.2967 eV, 0.16183 nm, 1626.8 cm−1, 20.8581 cm−1, 0.0611 cm−1 and 3.2468 cm−1, respectively; for the TI (X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are of 3.2144 eV, 3.2967 eV, 0.16183 nm, 1334.43 cm−1, 14.0765 cm−1, 0.0338 cm−1 and 2.1850 cm−1, respectively. These results accord well with the available experimental results. With the PEC of HI(X1Σ+) molecule obtained at present, a total of 19 vibrational states are predicted for the HI, 26 for the DI, and 32 for the TI, when the rotational quantum number J is equal to zero (J = 0). For each vibrational state, vibrational level G(v), inertial rotation constant Bv and centrifugal distortion constant Dv are determined when J = 0 for the first time, which are in excellent agreement with the experimental results. (atomic and molecular physics)
[en] We present the analytical results at the mean-field level for the asymmetrical fermion system with attractive contact interaction at zero temperature. The results can be expressed in terms of linear combinations of the elliptic integrals of the first and second kinds. In the limit of small gap parameter, we discuss how the asymmetry in fermion species affects the phases of the ground state of the system. In the limit of large gap parameter, we show that two candidate phases are competing for the system's ground state. The Sarma phase containing a pure Fermi fluid and a mixed condensate is favored at a large degree of asymmetry. The separated phase consisting of a pure Fermi fluid and a boson condensate supports the system at a small degree of asymmetry. The two phases are degenerate in the limit of infinite pairing gap
[en] The study of muonic atoms has yielded a variety of data on the distribution of the nuclear charge and magnetization and on the quadrupole deformation of nuclei (Devons, 1969; Wu and Wilets, 1969; Engfer et al., 1974); and more recently, on the change in the nuclear charge distribution between different nuclear states (Backe et al., 1974). The latter gives rise to what is usually called the muonic isomer shift, which is the subject of this chapter. The particular role the muon plays in probing the nucleus is primarily due to its mass being 207 times that of an electron. Consequently, the Bohr radii of muonic orbits are smaller by this factor. Actually they are so small that in muonic atoms with heavy nuclei the muon spends most of its time inside the nucleus. Clearly, the binding energy of the muon then depends sensitively on the proton distribution in the nucleus. Analogical to the Moessbauer isomer shift, the muonic isomer shift arises from the monopole term of the electrostatic interaction between the protonic charge distribution and the charge distribution of the leptons bound to the nucleus. (Auth.)
[en] The role of hybrid pairing originating from electron-phonon interaction has been investigated for a two band (f and d) superconductor at T = O. This type of pairing seems to be less important than f-f pairing for the case of half-filled f-band when the latter type of Cooper pairs plays the dominating role. On the other hand, for the case of rather filled (or rather empty) f-band, the superconducting properties of the system are mainly determined by the formation of conduction electrons d-d pairs. (author)
[en] This paper proposes the principle of SMES capacity determination for power system stable operation. Adopting the energy function method, the mechanism of SMES damping power oscillation in the classical single-machine infinite-bus (SMIB) system is analyzed. The released kinetic energy during disturbance is the original of power system oscillation, which is taken as the principle of SMES capacity determination. Then, the influence of fault type, fault position, and fault clearing time on the SMES capacity determination are discussed. Using MATLAB simulation, the principle of SMES capacity determination is evaluated.
[en] The quantum-statistical-mechanical (QSM) approach to molecular relaxation phenomena is employed to compare radiationless transitions originating from an electronic state characterized by a single minimum and double minima potential surface for a vibronically active, non-totally symmetric mode. The vibronic level dependence of the decay rates for these two cases has been investigated for both small and large energy gap transitions. It is shown that the behaviour of a molecular system is quite different for an initial state possessing a double minima potential surface as compared to the case in which the initial state possesses a single minimum. (Auth.)
[en] The transverse decoherence of the kicked beam due to amplitude dependent tune shift and the linear and the second order chromaticity are studied. For the kicked beam the closed analytical expression for the beam centroid evolution in subsequent turns is obtained. Analysis of the kicked beam centroid signal on the machine optical characteristics is given.