Density functional-time-dependent local density approximation calculations of autoionization resonances in noble gases

Abstract

Absolute photoionization cross section profiles and asymmetry parameters of Ne, Ar and Kr have been calculated at the time-dependent local density approximation level. We employed a very accurate B-spline finite basis set and the modified Sternheimer approach, which is a first-order perturbative scheme particularly suited to finite basis set calculations. The gradient-dependent van Leeuwen and Baerends (VLB) exchange-correlation potential has been used, since it has the correct Coulombic behaviour at large distances which is a necessary condition for the existence of the Rydberg states. A simple modification of the boundary conditions considerably improves the number of terms of the Rydberg series. The resonance parameters obtained by fitting the calculated Fano profiles with a suitable analytic expression are compared with the experimental parameters.

B-spline algebraic diagrammatic construction: Application to photoionization cross-sections and high-order harmonic generation

“…As it is possible to notice the ADC(1) result is overall closer to the experimental result by Samson et al,32 while the ADC(2) curve is closer to the experimental result by Chang et al 33 Both results are also in good agreement with the B-spline TDLDA theoretical calculations in Ref. 35, in which the correct normalization of the final continuum states was performed. It is worth noting that the Cooper minimum is due to a change of sign of the radial dipole matrix elements, which pass through zero at a certain energy, 34 and therefore it is already tractable within one-electron models such as the simple SAE (single active electron approach), as has been verified within LDA in Ref.…”

“…It is worth noting that the Cooper minimum is due to a change of sign of the radial dipole matrix elements, which pass through zero at a certain energy, 34 and therefore it is already tractable within one-electron models such as the simple SAE (single active electron approach), as has been verified within LDA in Ref. 35, although its precise energy position may be sensibly influenced by correlation effects. Moreover the possibility of describing properly the Cooper minimum feature is strongly related to the ability of the basis set to properly represent the continuum oscillating single-electron orbitals or, in other words, on the accuracy of the basis set in giving good representation of high order spectral moments in the Stieltjes imaging framework.…”

Improved density functional theory results for frequency-dependent polarizabilities, by the use of an exchange-correlation potential with correct asymptotic behavior

“…Mahan and Subbaswamy 17 prefer the partial SIC, which uses the self-interaction correction only for v xc and not for f xc , to full SIC, because the latter involves unphysical singularities. Stener et al 19 have used the model potential, which we employ here and which they called VLB-potential, in combination with time-dependent DFT to calculate autoionization resonances in noble gases. They used the simple X-␣ form for f xc , claiming that the Coulombic term in Equation ͑3͒, which is the second term on the right-hand side, is much more important for the screening than the exchange-correlation term.…”

“…Most calculations with time-dependent DFT have been restricted to atoms. [12][13][14][15][16][17][18][19] Molecular calculations were, among others, performed by Levine and Soven,20 in a single-center expansion. As this approach seems impractical for general systems, we recently developed a method which can be used for general molecules, although our present implementation can only handle closed-shell molecules.…”

Application of the time-dependent local density approximation to optical activity

“…The time-dependent local density approximation (TDLDA) as well as the time-dependent Hartree-Fock theory has been applied to the optical absorption of atomic and molecular systems with considerable success [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Here we want to see how well the TDLDA method does on a more subtle aspect of the optical response, the optical activity of chiral molecules.…”