scholarly journals Understanding Beam Induced Electronic Excitations in Materials

2019 ◽  
Author(s):  
David Lingerfelt ◽  
Panchapakesan Ganesh ◽  
Jacek Jakowski ◽  
Bobby Sumpter
Keyword(s):  
Point Charge ◽  
Scalar Potential ◽  
Transition Rates ◽  
Electronic Excitations ◽  
Consistent Field ◽  
External Point ◽  
Electronic Response ◽  
Self Consistent Field ◽  
Position Dependence ◽  
General Method

A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

scholarly journals Understanding Beam Induced Electronic Excitations in Materials

2019 ◽  
Author(s):  
David Lingerfelt ◽  
Panchapakesan Ganesh ◽  
Jacek Jakowski ◽  
Bobby Sumpter
Keyword(s):  
Point Charge ◽  
Scalar Potential ◽  
Transition Rates ◽  
Electronic Excitations ◽  
Consistent Field ◽  
External Point ◽  
Electronic Response ◽  
Self Consistent Field ◽  
Position Dependence ◽  
General Method

A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

scholarly journals First Principles Determination of Electronic Excitations Induced by Charged Particles

2019 ◽  
Author(s):  
David Lingerfelt ◽  
Panchapakesan Ganesh ◽  
Jacek Jakowski ◽  
Bobby Sumpter
Keyword(s):  
Point Charge ◽  
Scalar Potential ◽  
Charged Particles ◽  
Electronic Excitations ◽  
Consistent Field ◽  
External Point ◽  
Electronic Response ◽  
Self Consistent Field ◽  
General Method

A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

First Principles Determination of Electronic Excitations Induced by Charged Particles

2019 ◽  
Author(s):  
David Lingerfelt ◽  
Panchapakesan Ganesh ◽  
Jacek Jakowski ◽  
Bobby Sumpter
Keyword(s):  
Point Charge ◽  
Scalar Potential ◽  
Charged Particles ◽  
Electronic Excitations ◽  
Consistent Field ◽  
External Point ◽  
Electronic Response ◽  
Self Consistent Field ◽  
General Method

A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

scholarly journals First Principles Determination of Electronic Excitations Induced by Charged Particles

2019 ◽  
Author(s):  
David Lingerfelt ◽  
Panchapakesan Ganesh ◽  
Jacek Jakowski ◽  
Bobby Sumpter
Keyword(s):  
Point Charge ◽  
Scalar Potential ◽  
Charged Particles ◽  
Electronic Excitations ◽  
Consistent Field ◽  
External Point ◽  
Electronic Response ◽  
Self Consistent Field ◽  
General Method

A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

scholarly journals First Principles Determination of Electronic Excitations Induced by Charged Particles

2019 ◽  
Author(s):  
David Lingerfelt ◽  
Panchapakesan Ganesh ◽  
Jacek Jakowski ◽  
Bobby Sumpter
Keyword(s):  
Point Charge ◽  
Scalar Potential ◽  
Charged Particles ◽  
Electronic Excitations ◽  
Consistent Field ◽  
External Point ◽  
Electronic Response ◽  
Self Consistent Field ◽  
General Method

A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

scholarly journals A generalization of the equations of the self-consistent field for two-electron configurations

1937 ◽  
Vol 160 (903) ◽  
pp. 588-604 ◽  
Keyword(s):  
Wave Function ◽  
Differential Equations ◽  
Configuration Interaction ◽  
The Self ◽  
Angular Function ◽  
Radial Functions ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
General Method

The most successful general method so far devised for dealing with many- electron atoms is th a t of the self-consistent field (abbreviated in what follows to “ s. c. f.” ). If greater accuracy is required than is obtainable with the method as ordinarily used (either with or without exchange), either the so-called “ configuration interaction ” must be taken into account —usually a very laborious procedure—or else more complicated (varia­tional) methods must be used, which must be designed separately for each particular case, and in which the concept of each electron being assigned to its own “ orbit” is usually abandoned. It would seem desirable, therefore, to have, if possible, some general method which will increase the accuracy of the calculations without taking into account configuration interaction, and which will still allow the conceptual features of the s. c. f. method (i. e. the assignment of “ orbits” ) to be retained. In this paper such a method is developed for the case of two-electron configurations in Russell-Saunders coupling. The method consists in assuming a form for the wave function which is similar to that used in the s. c. f. method, except that the proper spatial symmetry is allowed for (which is not so in the case of the s. c. f. equations without exchange), and further, an adjustable function of Θ, the angle between the radii vectores to the two electrons, is inserted as a multiplying factor. The usual varia­tional method is then applied, and yields differential equations for the two radial functions which are similar to those of the ordinary theory, together with an equation for the angular function.

scholarly journals Excited States of Crystalline Point Defects with Multireference Density Matrix Embedding Theory

2021 ◽  
Author(s):  
Abhishek Mitra ◽  
Hung Pham ◽  
Riddhish Pandharkar ◽  
Matthew Hermes ◽  
Laura Gagliardi
Keyword(s):  
Density Matrix ◽  
Excited States ◽  
Open Shell ◽  
Electronic Excitations ◽  
Complete Active Space ◽  
Hartree Fock ◽  
Embedding Theory ◽  
Consistent Field ◽  
Matrix Embedding ◽  
Self Consistent Field

Accurate and affordable methods to characterize the electronic structure of solids are important for targeted materials design. Embedding-based methods provide an appealing balance in the trade-off between cost and accuracy - particularly when studying localized phenomena. Here, we use the density matrix embedding theory (DMET) algorithm to study the electronic excitations in solid-state defects with a restricted open-shell Hartree--Fock (ROHF) bath and multireference impurity solvers, specifically, complete active space self-consistent field (CASSCF) and n-electron valence state second-order perturbation theory (NEVPT2). We apply the method to investigate an oxygen vacancy (OV) on a MgO(100) surface and find absolute deviations within 0.05 eV between DMET using the CASSCF/NEVPT2 solver, denoted as CAS-DMET/NEVPT2-DMET, and the non-embedded CASSCF/NEVPT2 approach. Next, we establish the practicality of DMET by extending it to larger supercells for the OV defect and a neutral silicon-vacancy in diamond where the use of non-embedded CASSCF/NEVPT2 is extremely expensive.

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