scholarly journals Effects of quantum confinement on excited state properties ofSrTiO3fromab initiomany-body perturbation theory

2016 ◽  
Vol 94 (4) ◽  
Author(s):  
Sebastian E. Reyes-Lillo ◽  
Tonatiuh Rangel ◽  
Fabien Bruneval ◽  
Jeffrey B. Neaton
Keyword(s):  
Perturbation Theory ◽  
Excited State ◽  
Quantum Confinement

Photodynamic behavior of electronic coupling in a N-methylformamide dimer

2015 ◽  
Vol 17 (18) ◽  
pp. 12356-12364
Author(s):  
Martina Zámečníková ◽  
Dana Nachtigallová
Keyword(s):  
Perturbation Theory ◽  
Excited State ◽  
Electronic Coupling ◽  
Water Molecules ◽  
Complete Active Space ◽  
Active Space ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field

The role of the bridging water molecules has been studied during the excited state photodynamics of a N-methylformamide dimer in complex with water molecules employing the complete active space self-consistent field (CASSCF) and CAS perturbation theory (CASPT2) methods.

scholarly journals Решетки населенностей, создаваемые в газе атомов водорода с помощью ультрафиолетовых аттосекундных импульсов

2021 ◽  
Vol 129 (5) ◽  
pp. 627
Author(s):  
Р.М. Архипов ◽  
М.В. Архипов ◽  
А.В. Пахомов ◽  
Ю.М. Артемьев ◽  
Н.Н. Розанов
Keyword(s):  
Perturbation Theory ◽  
Approximate Solution ◽  
Excited State ◽  
Modulation Depth ◽  
Single Atom ◽  
Hydrogen Atoms ◽  
Central Frequency ◽  
Nonresonant Excitation ◽  
First Excited State ◽  
Attosecond Pulses

The possibility of population density grating in a gas of hydrogen atoms using a pair ultraviolet (UV) attosecond pulses that do not overlap in the medium is studied. Wherein the central frequency of the pulses can both coincide with the frequency of the resonant transition 1−2 from the main state in the first excited state (the main line of the Lyman series), and be detuned from it. The results of numerical calculations are in agreement with the analytical values ​​obtained on the basis of approximate solution of Schrödinger equation using perturbation theory. It is shown that under resonant excitation the greatest efficiency of the grating is achieved with an increase in the pulse duration. When nonresonant excitation, on the contrary, the system is more efficiently excited by short quasi-unipolar subcycle pulses than bipolar multicycle pulses. The results obtained can be applicable to coherent excitation of a single atom (thin layer) using a pair of UV pulses. The possibility of controlling the modulation depth of the gratings by changing the carrier envelope phase (CEP) of attosecond pulses is shown.

The long range van der Waals forces between non-identical systems

1965 ◽  
Vol 286 (1407) ◽  
pp. 573-587 ◽  
Keyword(s):  
Perturbation Theory ◽  
Excited State ◽  
Interaction Energy ◽  
Charge Distribution ◽  
Fourth Order ◽  
Ground State ◽  
Excited Molecule ◽  
Dipole Approximation ◽  
Two Systems ◽  
Energy Of Interaction

The interaction energy between two dissimilar non-ionized molecules or atoms is calculated in fourth-order perturbation theory and dipole approximation. The interaction Hamiltonian involves the charge distribution with the complete Maxwell field and not only the Coulomb interaction between charges. At close separations between the two systems (still large compared with molecular diameters) the interaction energy is of course that corresponding to the London force. However, for separations large compared with the characteristic wavelengths associated with transitions within the molecules the London force is modified considerably. In the case of two molecules in the ground state this modification was first found by Casimir & Polder. If one of the molecules is in an excited state new effects appear at these large distances. The energy of interaction depends on the orientation of the transition moment in the excited molecule with respect to the vector displacement between the two systems. In both transverse and longitudinal orientations the potential law is considerably stronger than the R -7 of the ground state-ground state interaction. For transverse orientations there is an unmodulated R -2 energy dependence which though very weak individually could give rise to considerable effects when the excited molecule is in a macroscopic environment.

Elektronenspektren p-donator-substituierter Benzonitrile und Benzoesäureäthylester/ Electronic Spectra of p-Donor Substituted Benionitriles and Ethylbenzoates

1983 ◽  
Vol 38 (3) ◽  
pp. 368-377 ◽  
Author(s):  
Günter Wermuth
Keyword(s):  
Perturbation Theory ◽  
Excited State ◽  
Electronic Spectra ◽  
Ester Group ◽  
Nitrile Group ◽  
The Other ◽  
Absorption Bands ◽  
Wave Numbers ◽  
Donor Substituent ◽  
Dialkylamino Group

Abstract The positions of 1La and 1Lb type absorption bands as well as the fluorescence polarization and natural lifetime show that p-donor substituted benzonitriles emit from a 1Lb-state. On the other hand, the nature of the lowest excited state of p-substituted ethylbenzoates depends upon the kind of the donor. In case of a dialkylamino group as donor substituent the emission occurs from the 1La-state, in case of weeker donors, like methoxy, from the 1Lb-state. In the intermediate case of p-aminoethylbenzoate the excited state depends upon the polarity of the solvent.The 1Lb← 1A transition occurs at higher wave numbers for the donor substituent ethylbenzoates than for the correspondingly substituted benzonitriles, although the ester group represents the stronger acceptor substituent than the nitrile group in spectroscopic respect. This effect is interpreted using perturbation theory according to Petruska.

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