Mel Levy
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View article: The Predictive Power of Exact Constraints and Appropriate Norms in Density Functional Theory
The Predictive Power of Exact Constraints and Appropriate Norms in Density Functional Theory Open
Ground-state Kohn-Sham density functional theory provides, in principle, the exact ground-state energy and electronic spin densities of real interacting electrons in a static external potential. In practice, the exact density functional fo…
View article: DFT Exchange: Sharing Perspectives on the Workhorse of Quantum Chemistry and Materials Science
DFT Exchange: Sharing Perspectives on the Workhorse of Quantum Chemistry and Materials Science Open
In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practiti…
View article: Can the Hartree-Fock kinetic energy exceed the exact kinetic energy?
Can the Hartree-Fock kinetic energy exceed the exact kinetic energy? Open
The Hartree-Fock (HF) approximation has been an important tool for quantum-chemical calculations since its earliest appearance in the late 1920s, and remains the starting point of most single-reference methods in use today. Intuition sugge…
View article: DFT Exchange: Sharing Perspectives on the Workhorse of Quantum Chemistry and Materials Science
DFT Exchange: Sharing Perspectives on the Workhorse of Quantum Chemistry and Materials Science Open
In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practiti…
View article: DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science
DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science Open
In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practiti…
View article: Scaling analysis of a physics-guided kinetic energy density expansion
Scaling analysis of a physics-guided kinetic energy density expansion Open
An approach guided by physical consistency in determining the general forms of D-dimensional kinetic energy density functionals (KEDF) has been demonstrated previously, producing an expansion which contains the majority of the known one-po…
View article: Simple hydrogenic estimates for the exchange and correlation energies of atoms and atomic ions, with implications for density functional theory
Simple hydrogenic estimates for the exchange and correlation energies of atoms and atomic ions, with implications for density functional theory Open
Exact density functionals for the exchange and correlation energies are approximated in practical calculations for the ground-state electronic structure of a many-electron system. An important exact constraint for the construction of appro…
View article: Time-independent density functional theory for degenerate excited states of Coulomb systems
Time-independent density functional theory for degenerate excited states of Coulomb systems Open
In this third paper of a series [Refs. Ayers–Levy–Nagy (Phys Rev A 85:042518, 2012; J Chem Phys 143:191101, 2015) are papers I and II], time-independent universal functionals of ensemble densities are identified for individual degenerate e…
View article: Nodal variational principle for excited states
Nodal variational principle for excited states Open
It is proven that the exact excited-state wave function and energy may be obtained by minimizing the energy expectation value of trial wave functions that are constrained only to have the correct nodes of the state of interest. This excite…
View article: Approximating the Shifted Hartree-Exchange-Correlation Potential in Direct Energy Kohn–Sham Theory
Approximating the Shifted Hartree-Exchange-Correlation Potential in Direct Energy Kohn–Sham Theory Open
Levy and Zahariev [Phys. Rev. Lett. 113 113002 (2014)] have proposed a new approach for performing density functional theory calculations, termed direct energy Kohn-Sham (DEKS) theory. In this approach, the electronic energy equals the sum…
View article: Highly Excited States from a Time Independent Density Functional Method
Highly Excited States from a Time Independent Density Functional Method Open
A constrained optimized effective potential (COEP) methodology proposed earlier by us for singly low-lying excited states is extended to highly excited states having the same spatial and spin symmetry. Basic tenets of time independent dens…
View article: Mathematical thoughts in DFT
Mathematical thoughts in DFT Open
A few problems in DFT are posed that have mathematical flavors. Is there a coordinate scaling equality for the correlation energy with an arbitrary density? Is it possible to obtain the exact ground‐state energy from the exact ground‐state…
View article: Communication: Kohn-Sham theory for excited states of Coulomb systems
Communication: Kohn-Sham theory for excited states of Coulomb systems Open
For obtaining individual excited-state energies and densities of Coulomb electronic systems, by means of an energy stationary principle, it was shown previously that there exists a universal functional of the density, FCoul[ϱ], for the kin…