arXiv subjects

Kieron Burke

Publications and source records attributed to Kieron Burke.

131 records · Page 8Linked to original sources

arXiv2000

Initial-state dependence in time-dependent density functional theory

Time-dependent density functionals in principle depend on the initial state of the system, but this is ignored in functional approximations presently in use. For one electron it is shown there is no initial-state dependence: for any density, only one initial state produces a well-behaved potential. For two non-interacting electrons with the same spin in one-dimension, an initial potential that makes an alternative initial wavefunction evolve with the same density and current as a ground state is calculated. This potential is well-behaved and can be made arbitrarily different from the original potential.

cond-mat.mtrl-sci↗

arXiv2000

A hybrid functional for the exchange-correlation kernel in time-dependent density functional theory

A review of the approximations in any time-dependent density functional calculation of excitation energies is given. The single-pole approximation for the susceptibility is used to understand errors in popular approximations for the exchange-correlation kernel. A new hybrid of exact exchange and adiabatic local density approximation is proposed and tested on the He and Be atoms.

cond-mat.mtrl-sci↗

arXiv2000

Excitation energies from time-dependent density functional theory using exact and approximate functionals

The role of the exchange-correlation potential and the exchange-correlation kernel in the calculation of excitation energues from time-dependent density functional theory is studied. Excitation energies of the He and Be atoms are calculated, both from the exact ground-state Kohn-Sham potential, and from two orbital-dependent approximations. These are exact exchange and self-interaction corrected local density approximation (SIC-LDA), both calculated using the Krieger-Li-Iafrate (KLI) approximation. For the exchange-correlation kernela, three adiabatic approximations were tested: The local density approximation, exact exchange, and SIC-LDA. The choice of the ground-state exchange-correlation potential has the largest impact on the absolute position of most excitation energies. In particular, orbital-dependent approximate potentials result in a uniform shift of the transition energies to the Rydberg states.

cond-mat.mtrl-sci↗

arXiv1999

Total energy density as an interpretative tool

We present an unambiguous formulation for the total energy density within density-functional theory. We propose that it be used as a tool for the interpretation of computed energy and electronic structure changes during structural transformations and chemical reactions, augmenting the present use of electron density changes and changes in the Kohn-Sham local density of states and Kohn-Sham energy density.

cond-mat.mtrl-sci↗

arXiv1999

Adiabatic connection from accurate wavefunction calculations

An extremely easy method for accurately calculating the adiabatic connection of density functional theory is presented, and its accuracy tested on both Hooke's atom and the He atom. The method is easy because calculations are needed only for different values of parameters in the external potential, which can be achieved with almost any electronic structure code.

cond-mat.mtrl-sci↗