Εξειδίκευση τύπου :	Κεφάλαιο βιβλίου
Τίτλος:	Resonances in the Continuum, Field-Induced Nonstationary States, and the State- and Property-Specific Treatment of the Many-Electron Problem
Δημιουργός/Συγγραφέας:	[EL] Νικολαΐδης, Κλεάνθης A.[EN] Nicolaides, Cleanthes A.
Εκδότης:	Academic Press Inc.
Ημερομηνία:	2017
Γλώσσα:	Αγγλικά
ISSN:	0065-3276
DOI:	10.1016/bs.aiq.2016.03.001
Περίληψη:	The paper summarizes elements of theories and computational methods that we have constructed and applied over the years for the nonperturbative solution of many-electron problems (MEPs), in the absence or presence of strong external fields, concerning resonance/nonstationary states with a variety of electronic structures. Using brief arguments and comments, I explain how these MEPs are solvable in terms of practical time-independent or time-dependent methods, which are based on single- or multistate Hermitian or non-Hermitian formulations. The latter result from the complex eigenvalue Schrödinger equation (CESE) theory. The CESE has been derived, for field free as well as for field-induced resonances, by starting from Fano's 1961 discrete-continuum standing-wave superposition, and by imposing outgoing-wave boundary conditions on the resulting solution. Regularization is effected via the use of complex coordinates for the orbitals of the outgoing electron(s) in each channel. The Hamiltonian coordinates remain real. The computational framework emphasizes the use of appropriate forms of the trial wavefunctions and the choice of function spaces according to the state- and property-specific methodology, using either nonrelativistic or relativistic Hamiltonians. In most cases, the bound part of excited wavefunctions is obtained via state-specific “HF or MCHF plus selected parts of electron correlation” schemes. This approach was first introduced to the theory of multiply excited and inner-hole autoionizing states in 1972, and its feasibility was demonstrated even in cases of multiply excited negative-ion scattering resonances. For problems of states interacting with strong and/or ultrashort pulses, the many-electron time-dependent Schrödinger equation is solved via the state-specific expansion approach. Applications have produced a plethora of numerical data that either compare favorably with measurements or constitute testable predictions of properties of N-electron field-free and field-induced nonstationary states.
Τίτλος πηγής δημοσίευσης:	Advances in Quantum Chemistry
Τόμος/Κεφάλαιο:	74
Σελίδες:	149-181
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Ατομική φυσική (συμπ. μοριακή φυσική, σχετικότητα, κβαντική θεωρία και φυσική στερεάς κατάστασης)[EN] Atomic physics (Incl. molecular physics, relativity, quantum theory, and solid state physics)
Λέξεις-Κλειδιά:	Complex eigenvalue Schrödinger equation Field-induced nonstationary states Many-electron problems Resonances Strong fields Time-dependent Schrödinger equation
Αξιολόγηση από ομότιμους (peer reviewed):	Ναι
Κάτοχος πνευματικών δικαιωμάτων:	© 2017 Elsevier Inc.
Όροι και προϋποθέσεις δικαιωμάτων:	All Open Access, Green
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο