1,721,185 research outputs found
Total molecular photoionization cross-sections by algebraic diagrammatic construction-Stieltjes-Lanczos method: Benchmark calculations
No full textIn [K. Gokhberg, V. Vysotskiy, L. S. Cederbaum, L. Storchi, F. Tarantelli, and V. Averbukh, J. Chem.
Phys. 130, 064104 (2009)] we introduced a new L2ab initio method for the calculation of total
molecular photoionization cross-sections. The method is based on the ab initio description of discretized
photoionized molecular states within the many-electron Green’s function approach, known
as algebraic diagrammatic construction (ADC), and on the application of Stieltjes-Chebyshev moment
theory to Lanczos pseudospectra of the ADC electronic Hamiltonian. Here we establish the
accuracy of the new technique by comparing the ADC-Lanczos-Stieltjes cross-sections in the valence
ionization region to the experimental ones for a series of eight molecules of first row elements:
HF, NH3, H2O, CO2, H2CO, CH4, C2H2, and C2H4. We find that the use of the second-order ADC
technique [ADC(2)] that includes double electronic excitations leads to a substantial systematic improvement
over the first-order method [ADC(1)] and to a good agreement with experiment for photon
energies below 80 eV. The use of extended second-order ADC theory [ADC(2)x] leads to a smaller
further improvement. Above 80 eV photon energy all three methods lead to significant deviations
from the experimental values which we attribute to the use of Gaussian single-electron bases. Our
calculations show that the ADC(2)-Lanczos-Stieltjes technique is a reliable and efficient ab initio
tool for theoretical prediction of total molecular photo-ionization cross-sections in the valence region
Band shape and vibrational structure in Auger spectra: Theory and application to carbon monoxide
No full textMicrosolvation of Li+ in water analyzed by ionization and double ionization
No full textThe microsolvation of Li+ in water is investigated. The ionization and double-ionization spectra of the series
of (H2O)nLi+ (n = 1-5) clusters are calculated ab initio by Green’s function methods and discussed in detail.
The impact of the solvation of the lithium cation with an increasing number of water molecules on the spectral
characteristics is revealed. In the context of microsolvation, the discussion of the results for the (H2O)5Li+
cluster is particularly important because the second solvation shell is accessed. Ionization- and double-ionization
spectra may be considered to be very useful for the study of microsolvation clusters
Doubly ionized states of ethylene: Auger spectrum, potential energy surfaces and nuclear dynamics
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