Comparison of the strong-field ionization ofN2andF2: A time-dependent density-functional-theory study

Abstract

We compare strong-field ionization probabilities of N 2 and F 2 molecules using time-dependent density functional theory calculations. Accurate nuclear potentials and ground vibrational wave functions are incorporated into our study. For both molecules, the effect of molecular vibration is small, while that of the molecular orientation is significant. When compared to the ionization probability of a molecule at the equilibrium geometry, we estimate the effect of the ground state vibration to be within 3% for N 2 and within 6% for F 2 in the intensity range from 1 to 5 × 10 14 W/cm 2 . The molecular-orientation-dependent ionization probabilities for both molecules at various intensities are presented. They are strongly dependent on the laser intensity, and the anisotropy diminishes when the laser intensity is high. For laser intensities of 1.6 and 2.2 × 10 14 W/cm 2 we find ionization probability ratios of 5.9 and 4.3, respectively, for the parallel versus perpendicular orientation of N 2 . This is reasonably consistent with experimental measurements. For randomly oriented molecules, the ratio of the probabilities for N 2 and F 2 increases from about 1 at 10 14 W/cm 2 to 2 at 4 × 10 14 W/cm 2 , which agrees well with experimental results.

Role of resonance-enhanced multiphoton excitation in high-harmonic generation of N2: A time-dependent density-functional-theory study

“…An important question, however, is: What makes the HOMO (3σ g ) atomic-like? An earlier study of ours showed that the projection of the outer region of the 3σ g orbital is 82.7% s and 17.1% d z 2 [27]. This ratio varies with the radius r. Dipole matrix elements involving the d z 2 orbital depend on the orientation.…”

“…Later this work was extended to treat arbitrary polarization directions for the study of the anisotropy of ionization and HHG [27,33,34]. We use the approach of Ref.…”

“…The α parameters of the TDLB α potential for different R values are listed in Ref. [27]. We show the HHG spectra in Fig.…”

Time-dependent density-functional-theory study of the suppressed tunneling ionization of vanadium

“…The quantum action A[ ] has a stationary point at the TD density of the system, and hence from the Euler equation we get the working equations [20,21]. When we project Eq.…”

Analytical model for calibrating laser intensity in strong-field-ionization experiments

“…Accurate calculations of ionization probability for a fixed laser intensity can be accomplished by solving the timedependent Schrödinger equation (TDSE) for atoms and some small molecules [8][9][10][11][12][13][14][15][16][17][18][19], mostly based on the single-activeelectron (SAE) model. Calculations including all electrons in the atom or molecules have been used within the timedependent density functional theory (TDDFT) [20][21][22][23][24][25], the time-dependent Hartree-Fock (TDHF) theory [26,27], or the multiconfiguration time-dependent Hartree-Fock (MCTDHF) theory [28][29][30]. These calculations are very time-consuming and their accuracy is also difficult to judge.…”