Adiabatic connection in density functional theory in two-dimensions: A semi-analytic wavefunction based study for two-electron atomic systems

2019 ◽  
Vol 151 (20) ◽  
pp. 204104
Author(s):  
Rabeet Singh ◽  
Bikash Patra ◽  
Abhilash Patra ◽  
Manoj K. Harbola ◽  
Prasanjit Samal
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Two Dimensions ◽  
Functional Theory ◽  
Atomic Systems

scholarly journals What Do We Learn from the Classical Turning Surface of the Kohn-Sham Potential as Electron Number Is Varied Continuously?

2019 ◽  
Author(s):  
Tim Gould ◽  
Benjamin Libereles ◽  
John P. Perdew
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Principal Quantum Number ◽  
Ionisation Potential ◽  
Electron Number ◽  
Conceptual Density Functional Theory ◽  
Functional Theory ◽  
Atomic Systems ◽  
Additional Information ◽  
Turning Radius

The classical turning radius Rt of an atom can be defined as the radius where the KS potential is equal to the negative ionisation potential of the atom, i.e. where v_s(R_t)=\epsilon_h. It was recently shown [P.N.A.S. 115, E11578 (2018)] to yield chemically relevant bonding distances, in line with known empirical values. In this work we show that extension of the concept to non-integer electron number yields additional information about atomic systems, and can be used to detect the difficulty of adding or subtracting electrons. Notably, it reflects the ease of bonding in open p-shells, and its greater difficulty in open s-shells. The latter manifests in significant discontinuities in the turning radius as the electron number changes the principal quantum number of the outermost electronic shell (e.g. going from Na to Na^{2+}). We then show that a non-integer picture is required to correctly interpret bonding and dissociation in H_2^+. Results are consistent when properties are calculated exactly, or via an appropriate approximation. They can be interpreted in the context of conceptual density functional theory.

Density functional theory (DFT) study of BaScO3H0.5 compound and its hydrogen storage properties

2019 ◽  
Vol 97 (11) ◽  
pp. 1191-1199 ◽  
Author(s):  
Aysenur Gencer ◽  
Gokhan Surucu
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Storage ◽  
Density Functional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Stable Phase ◽  
Partial Density ◽  
Functional Theory ◽  
Hydrogen Storage Properties ◽  
Storage Properties

BaScO3 and its hydride BaScO3H0.5 have been investigated using density functional theory (DFT) with the generalized gradient approximation (GGA). BaScO3 perovskite can crystallize in five possible crystal structures: orthorhombic (Pnma), tetragonal (P4mm), rhombohedral (R-3c), hexagonal (P63/mmc), and cubic (Pm-3m). These five possible phases have been optimized to obtain the most stable phase of BaScO3. The orthorhombic phase, being the most stable and having the lowest volume among the studied phases, has been considered for hydrogen bonding studies, and BaScO3H0.5 has been obtained. The electronic properties including band structure and corresponding partial density of states have been obtained for both BaScO3 and BaScO3H0.5 compounds. In addition, partial charge analysis has been performed. The calculated elastic constants have been used to obtain mechanical properties, such as bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio. Also, direction-dependent elastic properties have been studied in two dimensions and three dimensions. BaScO3 and BaScO3H0.5 compounds have ionic bonding and they are ductile materials. Moreover, the hydrogen storage properties of BaScO3H0.5 have been investigated and it is found that the gravimetric hydrogen storage capacity is 0.22 wt% and the hydrogen desorption temperature is determined as 1769.70 K.

On the shape of spherically averaged Fermi-hole correlation functions in density functional theory. 1. Atomic systems

1989 ◽  
Vol 67 (3) ◽  
pp. 460-472 ◽  
Author(s):  
Vincenzo Tschinke ◽  
Tom Ziegler
Keyword(s):  
Density Functional Theory ◽  
Correlation Function ◽  
Energy Density ◽  
Density Functional ◽  
Exchange Energy ◽  
Energy Density Functional ◽  
Functional Theory ◽  
Atomic Systems ◽  
Hartree Fock ◽  
Fermi Hole

We have compared, for atomic systems, the spherically averaged Fermi-hole correlation function [Formula: see text] in the Hartree–Fock theory with the corresponding function [Formula: see text] employed in local density functional theory. It is shown that, in contrast to [Formula: see text], the function [Formula: see text] behaves qualitatively incorrectly at positions r1 of the reference electron far from the nucleus. Furthermore, we have shown that the qualitatively incorrect behaviour of [Formula: see text] can be remedied by an approximate expansion of [Formula: see text] in powers of s, where s is the inter-electronic distance. However, such an expansion must be conducted in two regions due to the discontinuity of [Formula: see text] as a function of s at the atomic nucleus. Based on the two-region expansion of [Formula: see text] we have developed an alternative approximate density functional expansion [Formula: see text] for the spherically averaged Fermi-hole correlation function. The corresponding exchange energy density functional yields values for the exchange energies of atoms in good agreement with Hartree–Fock results. Keywords: atomic exchange energy, density functional theory, Fermi hole.

scholarly journals What Do We Learn from the Classical Turning Surface of the Kohn-Sham Potential as Electron Number Is Varied Continuously?

2019 ◽  
Author(s):  
Tim Gould ◽  
Benjamin Libereles ◽  
John P. Perdew
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Principal Quantum Number ◽  
Ionisation Potential ◽  
Electron Number ◽  
Conceptual Density Functional Theory ◽  
Functional Theory ◽  
Atomic Systems ◽  
Additional Information ◽  
Turning Radius

The classical turning radius Rt of an atom can be defined as the radius where the KS potential is equal to the negative ionisation potential of the atom, i.e. where v_s(R_t)=\epsilon_h. It was recently shown [P.N.A.S. 115, E11578 (2018)] to yield chemically relevant bonding distances, in line with known empirical values. In this work we show that extension of the concept to non-integer electron number yields additional information about atomic systems, and can be used to detect the difficulty of adding or subtracting electrons. Notably, it reflects the ease of bonding in open p-shells, and its greater difficulty in open s-shells. The latter manifests in significant discontinuities in the turning radius as the electron number changes the principal quantum number of the outermost electronic shell (e.g. going from Na to Na^{2+}). We then show that a non-integer picture is required to correctly interpret bonding and dissociation in H_2^+. Results are consistent when properties are calculated exactly, or via an appropriate approximation. They can be interpreted in the context of conceptual density functional theory.

DENSITY FUNCTIONAL THEORY AND STATISTICAL GAUGE FIELDS

1993 ◽  
Vol 07 (29n30) ◽  
pp. 1941-1946
Author(s):  
MICHAEL R. GELLER
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Two Dimensions ◽  
Gauge Potential ◽  
Gauge Fields ◽  
Recent Proposal ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Correlation Vector ◽  
Chern Simons

We consider the possibility that the exchange-correlation vector potential of density functional theory and the Chern-Simons gauge potential, used to change the statistics of particles in two dimensions, are related. By comparing the corresponding gauge invariant field strengths and their dependence on density and external magnetic field, we find no connection between these two potentials, in contrast to a recent proposal.

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