A subspace formulation of time-dependent density functional theory (TDDFT) is proposed for large-scale calculations based on density functional perturbation theory. The formulation is implemented in conjunction with projector augmented-wave method and plane-wave basis set. A key bottleneck of conventional TDDFT method is circumvented by projecting the time-dependent Kohn-Sham eigenvalue equatio...

A method is developed for using large-order perturbation theory to solve the systems of coupled diierential equations that result from variational solution of the Schrr odinger equation with wavefunctions of product form. This is a noniterative, computationally eecient way to solve self-consistent-eld (SCF) equations. Possible applications include electronic structure calculations using product...

We consider the Born-Oppenheimer problem near conical intersection in two dimensions. For energies close to the crossing energy we describe the wave function near an isotropic crossing and show that it is related to generalized hypergeometric functions 0F3. This function is to a conical intersection what the Airy function is to a classical turning point. As an application we calculate the anoma...

J. Robert Oppenheimer, ambitious leader of the Manhattan Project, struggled with intense ethical dilemmas. To continue to work on the atom bomb, he had to abandon his communist friends in order to prove to military monitors his loyalty to the US government. Later, Oppenheimer faced the moral implications of the project’s success. His struggles with ambition, betrayal, and moral quandaries made ...

We present a time-reversible Born-Oppenheimer molecular dynamics scheme, based on self-consistent Hartree-Fock or density functional theory, where both the nuclear and the electronic degrees of freedom are propagated in time. We show how a time-reversible adiabatic propagation of the electronic degrees of freedom is possible despite the nonlinearity and incompleteness of the self-consistent fie...

We propose to expand the nonadiabatic solution of the Schrödinger equation as a linear combination of explicitly correlated exponentials. A series of trial wavefunctions has been optimized minimizing the variance of the local energy for the H2 + and dipositronium (Ps2) molecules in their ground state, without resorting to the Born-Oppenheimer approximation: the calculations have been performed ...

Whereas the search for the degeneracy points which are better known as conical intersections (or ci-points) is usually carried out with a lot of devotion, the nonadiabatic coupling terms (NACTs) which together with the adiabatic potential energy surfaces appear in the nuclear Born-Oppenheimer-Schrodinger equation are ignored in most dynamical calculations. In the present article we consider two...

Here we consider one of the basic models for many-body problems under an external field: the molecule ion H+2 under the effect of an external Stark-type potential. If we consider the vibrational energy levels of the first two electronic states of the molecule ion H+2 then, in the semiclassical limit and by means of a suitable modified Born-Oppenheimer method, we can prove that they switch to sh...