Ab initiocalculation of interatomic decay rates by a combination of the Fano ansatz, Green’s-function methods, and the Stieltjes imaging technique

Abstract

A new computational technique is introduced for the ab initio calculation of the rates of interatomic and intermolecular nonradiative decay processes occurring due to electronic correlation. These recently discovered phenomena are described theoretically using the configuration-interaction formalism first introduced by Fano [Phys. Rev. 124, 1866 (1961)] and later adapted to an Auger decay by Howat et al. [J. Phys. B 11, 1575 (1978)]. The boundlike and the continuumlike components of the wave function of the decaying state are constructed using a Green's-function method known as algebraic diagrammatic construction. A combination of atomic and distributed Gaussian basis sets is shown to provide an adequate description of both boundlike and continuumlike wave-function components. The problem of the normalization of the continuum (final state) wave function is addressed using the Stieltjes imaging technique. The new method is applied to the calculation of the rates of interatomic decay in alkaline-earth-rare-gas clusters. The obtained results help to verify our earlier conclusions [Phys. Rev. Lett. 93, 263002 (2004)] regarding the validity of the virtual-photon transfer model for the interatomic Coulombic decay. In addition, we demonstrate that the process of electron-transfer-mediated decay is responsible for the finite lifetimes of the outer valence vacancies in alkaline-earth-rare-gas clusters.

The role of metal ions in X-ray-induced photochemistry

“…The electron integrals and molecular orbitals serving as input for the propagator based computations were calculated by MOLCAS 7.4 software package [44]. The energies of pentacationic states were obtained by multi-reference configuration interaction method including single and double excitations (DIRECT-CI) [45] implemented in the GAMESS-UK 8.0 quantum chemistry package [46] The total and partial electronic decay widths were calculated by means of Fano-ADCStieltjes method [16,47]. Due to numerical limitations, the decay widths for the Mg 4+ (H 2 O) 6 states were determined in an additive approximation [48,49].…”

“…They fulfil a number of important roles in biological systems, such as being instrumental for the catalytic activity of enzymes [1,2] or ensuring structural stability of chromosomes [3,4]. In this report we investigate what is the role of these naturally occurring metal species in radiation damage or, more broadly, X-ray induced photochemistry of biological systems.…”

“…The ETMD(2) to ETMD(3) branching ratio is 1.0/1.6, therefore, both H 2 O + and H 2 O 2+ are efficiently produced in the ionisation of the medium. The final products are either Mg 4 ; the charge on Mg decreases by one as the result of electron transfer from water (see Fig.1). The ETMD electrons have energies between 11 and 26 eV for ETMD (2) and between 23 and 40 eV for ETMD (3).…”

“…The corresponding lifetime is 15.5 fs, while the emitted electrons have energies of 0-6 and 5-19 eV, respectively. Following this decay step the 4 species are produced with the ratio of 1.0 to…”

A comprehensive study of Interatomic Coulombic Decay in argon dimers: Extracting R-dependent absolute decay rates from the experiment

“…The latter theoretical calculation was performed using the Fano-ADC-Stieltjes method [42]. The bound and continuum parts of the resonance states as well as the coupling between them were constructed using the extended ADC(2) scheme for the one-particle propagator [43].…”