TIME-BRIDGE aims at solving the time-scale problem by borrowing a concept well known and developed in the field of first-principles simulations: the pseudopotential
He covers the fundamentals and methods of electronic structure, including quantum description of matter, the density functional theory, basic energy band theory, Green's function, disordered alloys, first-principles molecular dynamics, general principles associated with materials design, and methods of electronic structure calculations, such as pseudopotential
, the Korringa-Kohn-Rostoker method, and augmented plane wave methods.
These scientists created a program entitled Pseudopotential Algorithms for Real Space Eigenvalue Calculations (PARSEC) on which RSDFT is based.
The ionic potential is approximated by a pseudopotential proposed by Shaw in .
Indeed, there is a request of presence of repulsive potential interaction between identical kind of particles (recall S-wave repulsive pseudopotential
interaction between atoms in the superfluid liquid [sup.
So, to sum it up: a semilocal pseudopotential is a general Hermitian operator in the spherically symmetric problem (i.
and finally we arrive at the separable form of the l dependent pseudopotential
More ab initio theories directly calculate the full electronic states of the system, typically calculating the contribution of each atom to the electronic potential self-consistently within density functional or pseudopotential
theory (see for example A.
Approximate methods are treated next, starting with spin separation in the Dirac equation, and proceeding to the Foldy-Wouthuysen, Douglas-Kroll, and related transformations, Breit-Pauli and direct perturbation theory, regular approximations, matrix approximations, and pseudopotential
and model potential methods.
is the Fourier transform of a S-wave pseudopotential
in the momentum space:
The resulting pseudopotential
confines the ions radially in a well with a secular frequency [v.
267 TROULLIER N,PHYS REV B,vol 0043,page 1993,1991,cites= 126,EFFICIENT PSEUDOPOTENTIALS FOR PLANE-WAVE CALCULATIONS