9 research outputs found
Cubic scaling algorithms for RPA correlation using interpolative separable density fitting
We present a new cubic scaling algorithm for the calculation of the RPA
correlation energy. Our scheme splits up the dependence between the occupied
and virtual orbitals in by use of Cauchy's integral formula. This
introduces an additional integral to be carried out, for which we provide a
geometrically convergent quadrature rule. Our scheme also uses the newly
developed Interpolative Separable Density Fitting algorithm to further reduce
the computational cost in a way analogous to that of the Resolution of Identity
method.Comment: 22 pages, 6 figure
Dissociation limit of the H2 molecule in the particle-hole random phase approximation
In this work, we consider the particle-hole random phase approximation
(phRPA), an approximation to the correlation energy in electronic structure,
and show that the phRPA energy of the H2 molecule correctly dissociates. That
is, as the hydrogen atoms are pulled apart, the phRPA energy of the system
converges to twice the phRPA energy of a single hydrogen atom. Despite the
simplicity of the H2 system, the correct dissociation of H2 is known to be a
difficult problem for density functional approximations. As part of our result,
we prove that the phRPA correlation energy is well-defined