scholarly journals Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses

2020 ◽  
Vol 152 (7) ◽  
pp. 071102 ◽  
Author(s):  
Håkon Emil Kristiansen ◽  
Øyvind Sigmundson Schøyen ◽  
Simen Kvaal ◽  
Thomas Bondo Pedersen
Keyword(s):  
Numerical Stability ◽  
Laser Pulses ◽  
Time Dependent ◽  
Intense Laser ◽  
Coupled Cluster ◽  
Electron Dynamics ◽  
Coupled Cluster Methods ◽  
Intense Laser Pulses ◽  
Cluster Methods

Nonlinear time-dependent density functional theory investigation and visualization of ionizations in CO2 — Effects of laser intensities and molecular orientations

2010 ◽  
Vol 88 (11) ◽  
pp. 1186-1194
Author(s):  
Emmanuel Penka Fowe ◽  
André Dieter Bandrauk
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Laser Pulses ◽  
Time Dependent ◽  
Intense Laser ◽  
Functional Theory ◽  
Intense Laser Pulses ◽  
Highest Occupied Molecular Orbital ◽  
Analysis Of The Images ◽  
Dependent Density

Time-dependent density functional theory (TDDFT) studies of the ionization of CO2 by intense laser pulses Io ≥ 1 × 1014 W/cm2, at 800 nm are presented using the LB94 and the LDA potentials. Results reveal that for lower laser peak intensity, Io = 3.5 × 1014 W/cm2, the highest occupied molecular orbital (HOMO) contributes significantly to ionization owing to its lower ionization potential (IP), whereas the inner orbitals play the important role for higher laser peak intensities. Even though such lower orbitals have higher IP, the ionization process occurs when orbital densities are maximum along the direction of the laser field polarization. These findings are confirmed through the analysis of the images from the time-dependent electron localization function (TDELF) and the spectra of higher order harmonic generation (HOHG). Additionally, in spite of the IP difference between Kohn–Sham orbitals from LDA and LB94 potentials, our results show almost the same trend for both.

HARMONIC GENERATIONS OF CLUSTER Na2 IN ULTRASHORT INTENSE LASER PULSES

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2687-2692 ◽  
Author(s):  
F. S. ZHANG ◽  
F. WANG ◽  
Y. ABE
Keyword(s):  
Harmonic Generation ◽  
Local Density ◽  
Laser Pulses ◽  
Time Dependent ◽  
Intense Laser ◽  
Density Approximation ◽  
The Third ◽  
Intense Laser Pulses ◽  
Laser Frequencies ◽  
Ponderomotive Potential

In the framework of the time dependent local density approximation the harmonic generation of Na2 in ultrashort intense pulses is investigated. The coupling between harmonics and plasmons of Na 2 is discussed in detail with two laser frequencies 5.266 eV, which is double the resonance of the plasmon, and 1.124 eV, which is half the frequency of plasmons, and with two different peak intensities. One finds appearance of the third and the fifth harmonic generation at high ponderomotive potential.

Nonlinear time-dependent density functional theory studies of the ionization of CO2 by ultrashort intense laser pulses

2009 ◽  
Vol 87 (7) ◽  
pp. 1081-1089
Author(s):  
Emmanuel Penka Fowe ◽  
André Dieter Bandrauk
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Laser Pulses ◽  
Time Dependent ◽  
Intense Laser ◽  
Functional Theory ◽  
Intense Laser Pulses ◽  
Highest Occupied Molecular Orbital ◽  
Dependent Density

Time-dependent density functional theory (TDDFT) studies of the ionization of CO2 by intense laser pulses (3.50 × 1014, 1.40 × 1015, 2.99 × 1015, and 1.25 × 1016 W/cm2) at 800 nm (ω = 0.0584 au) are presented in the nonlinear nonpertubative regime. Special emphasis is placed on elucidating molecular orbital orientation and various peak-intensities effects on the ionization processes. The results reveal that molecular orbital ionizations are strongly sensitive to their symmetry and the laser intensities. Most notably, we found that with a proper choice of the laser intensity (3.5 × 1014 W/cm2), the sensitivity is strong enough such that the nature and symmetry of the highest occupied molecular orbital (HOMO) can be directly probed and visualized from the angular dependence of laser-induced ionization. At higher intensities, ionization is found to occur also from inner orbitals, thus complicating the imaging of simple orbitals. A time-dependent electron-localization function (TDELF) is used to get a visual insight on the time evolution process of the electron density.

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