Arbitrary Choice of Basic Variables in Density Functional Theory. I. Formalism

The Hohenberg-Kohn theorem of the density functional theory is extended by modifying the Levy constrained-search formulation. The new theorem allows us to choose arbitrary physical quantities as the basic variables which determine the ground-state properties of the system. Moreover, the theorem establishes a minimum principle with respect to variations in the chosen basic variables as well as with respect to variations in the density. By using this theorem, the self-consistent single-particle equations are derived. N single-particle orbitals introduced reproduce the basic variables. The validity of the theory is confirmed by the examples where the spin-density or paramagnetic current-density is chosen as one of the basic variables. The resulting single-particle equations coincide with the Kohn-Sham equations of the spin-density functional theory (SDFT) or current-density functional theory (CDFT), respectively. By choosing basic variables appropriate to the system, the present theory can describe the ground-state properties more efficiently than the conventional DFT.Comment: 23 pages, 1 figure, Changed conten

Density functional scheme for calculating the pair density

The density functional scheme for calculating the pair density is presented by means of the constrained-search technique. The resultant single-particle equation takes the form of the modified Hartree-Fock equation which contains the kinetic contribution of the exchange-correlation energy functional as the correlation potential. The practical form of the kinetic contribution is also proposed with the aid of the scaling relations of the kinetic energy functionals.Comment: 5 page

Delivering Diabetes Care in the Philippines and Vietnam: Policy and Practice Issues

The aim of this study is the comparison of 2 studies looking at the barriers to access of diabetes care and medicines in the Philippines and Vietnam. These studies used the Rapid Assessment Protocol for Insulin Access. Diabetes care is provided in specialized facilities and appropriate referral systems are lacking. In Vietnam, no problems were reported with regard to diagnostic tools, whereas this was a concern in the public sector in the Philippines. Both countries had high prices for medicines in comparison to international standards. Availability of medicines was better in Vietnam than in the Philippines, especially with regard to insulin. This affected adherence as did a lack of patient education. As countries aim to provide health care to the majority of their populations through universal coverage, the challenge of diabetes cannot be neglected. Trying to achieve universal coverage in parallel to decentralization, national and local governments need adapted guidance for this

Electronic structure and the Fermi surface of UTGa_{5} (T=Fe, Co, Rh)

The relativistic energy-band calculations have been carried out for UFeGa_{5}, UCoGa_{5} and URhGa_{5} under the assumption that 5f-electrons are itinerant. A hybridization between the U 5f state and Ga 4p state occurs in the vicinity of the Fermi level. The Fermi surface of UCoGa_{5} is quite similar to that of URhGa_{5}, which are all small in size and closed in topology. UFeGa_{5} has the quasi-two-dimensional Fermi surface which looks like a lattice structure.Comment: 2 pages, 3 figures, LT23auth.cls, elsart.cls. submitted to conference LT2

Renormalization group approach to multiple-arc random matrix models

We study critical and universal behaviors of unitary invariant non-gaussian random matrix ensembles within the framework of the large-N renormalization group. For a simple double-well model we find an unstable fixed point and a stable inverse-gaussian fixed point. The former is identified as the critical point of single/double-arc phase transition with a discontinuity of the third derivative of the free energy. The latter signifies a novel universality of large-N correlators other than the usual single arc type. This phase structure is consistent with the universality classification of two-level correlators for multiple-arc models by Ambjorn and Akemann. We also establish the stability of the gaussian fixed point in the multi-coupling model.Comment: 11 pages, 1 figure, LaTeX + a4.sty, epsf.st

Sum rules for the exchange-correlation energy functional of the extended constrained-search theory: Application to checking the validity of the vorticity expansion approximation of the current-density functional theory

We present four kinds of sum rules for the exchange-correlation energy functional of the extended constrained-search theory. They are applicable even to the conventional density functional theory. As an application of these sum rules, we utilize them to check the validity of the vorticity expansion approximation (VEA) of the current-density functional theory (CDFT). The VEA formula fulfils three of them, though the local density approximation formula of the CDFT fulfills only one. The validity of the VEA formula is thus confirmed successfully from the viewpoint of the sum rules.ArticlePHYSICAL REVIEW A. 81(4):042505 (2010)journal articl

Scheme for calculating the orbital-dependent exchange-correlation potential using the virial theorem: Application to atomic systems

We present a density-functional scheme for calculating the orbital-dependent exchange-correlation potential using the virial theorem as a sum rule. In order to check the validity of this scheme, atomic-structure calculations only with the exchange potential are performed. The accuracy of this scheme is shown to be comparable to that of the optimized effective potential (OEP) method, while the computational workload is extremely reduced compared to the OEP method.ArticlePHYSICAL REVIEW A. 78(1):012501 (2008)journal articl

Tree-level Scattering Amplitude in de Sitter Space

In previous papers [1,2], it was proved that a covariant quantization of the minimally coupled scalar field in de Sitter space is achieved through addition of the negative norm states. This causal approach which eliminates the infrared divergence, was generalized further to the calculation of the graviton propagator in de Sitter space [3] and one-loop effective action for scalar field in a general curved space-time [4]. This method gives a natural renormalization of the above problems. Pursuing this approach, in the present paper the tree-level scattering amplitudes of the scalar field, with one graviton exchange, has been calculated in de Sitter space. It is shown that the infrared divergence disappears and the theory automatically reaches a renormalized solution of the problem.Comment: 6 page

Aspects of Localized Gravity Around the Soft Minima

n-Dimensional pure gravity theory can be obtained as the effective theory of an n+1 model (with non-compact extra dimension) where general n+1 reparametrization invariance is explicitly broken in the extra dimension. As was pointed out in the literature, a necessary consistency condition for having a non-vanishing four dimensional Newton constant is the normalizability in the extra dimension of the zero mass graviton. This, in turn, implies that gravity localization is produced around the local minima of a potential in the extra dimension. We study gravity in the neighborhood of the soft ("thick") local minima.Comment: 13 pages, 3 figure

Decay of the free-theory vacuum of scalar field theory in de Sitter spacetime in the interaction picture

A free-theory vacuum state of an interacting field theory, e.g. quantum gravity, is unstable at tree level in general due to spontaneous emission of Fock-space particles in any spacetime with no global timelike Killing vectors, such as de Sitter spacetime, in the interaction picture. As an example, the rate of spontaneous emission of Fock-space particles is calculated in phi^4 theory in de Sitter spacetime. It is possible that this apparent spontaneous emission does not correspond to any physical processes because the states are not evolved by the true Hamiltonian in the interaction picture. Nevertheless, the constant spontaneous emission of Fock-space particles in the interaction picture clearly demonstrates that the in- and out-vacuum states are orthogonal to each other as emphasized by Polyakov and that the in-out perturbation theory, which presupposes some overlap between these two vacuum states, is inadequate. Other possible implications of apparent vacuum instability of this kind in the interaction picture are also discussed.Comment: title changed, 7 page