scholarly journals THE STEEPEST DESCENT PERTURBATION THEORY FOR THE EXCITED STATE OF A QUANTUM SYSTEM

1991 ◽  
Vol 40 (9) ◽  
pp. 1388
Author(s):  
WEN GEN-WANG
Keyword(s):  
Perturbation Theory ◽  
Excited State ◽  
Quantum System ◽  
Steepest Descent

scholarly journals A strongly perturbed quantum system is a semiclassical system

2007 ◽  
Vol 463 (2085) ◽  
pp. 2195-2200 ◽  
Author(s):  
Marco Frasca
Keyword(s):  
Perturbation Theory ◽  
Quantum System ◽  
Perturbation Series ◽  
Duality Principle

We show that a strongly perturbed quantum system, being a semiclassical system characterized by the Wigner–Kirkwood expansion for the propagator, has the same expansion for the eigenvalues as for the Wentzel–Kramers–Brillouin series. The perturbation series is rederived by the duality principle in perturbation theory.

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 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

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.

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