Low-Order Scaling G0W0 by Pair Atomic Density Fitting

Linear scaling density fitting.

Two modifications of the resolution of the identity (RI)/density fitting (DF) approximations are presented. First, we apply linear scaling and J-engine techniques to speed up traditional DF. Second, we develop an algorithm that produces local, accurate fits with effort that scales linearly with system size. The fits produced are continuous, differentiable, well-defined, and do not require prese...

Towards solution and refinement of organic crystal structures by fitting to the atomic pair distribution function.

A method towards the solution and refinement of organic crystal structures by fitting to the atomic pair distribution function (PDF) is developed. Approximate lattice parameters and molecular geometry must be given as input. The molecule is generally treated as a rigid body. The positions and orientations of the molecules inside the unit cell are optimized starting from random values. The PDF i...

Local structure of random InxGa1 xAs alloys by full-profile fitting of atomic pair distribution functions

The local structure of random InxGa1 xAs alloys has been refined by fitting experimental high-resolution atomic pair distribution functions with the 8-atom unit cell of the zinc-blende lattice. Both metal and As atoms have been allowed to move off their ideal positions and so the local structural disorder due to the presence of two distinct bond lengths, Ga–As and In–As, has been quantified. It...

Pair density distribution function of membrane particles at low density.

Atomic pair distribution functions analysis of disordered low-Z materials.

Results of high-energy X-ray diffraction experiments coupled to atomic pair distribution function analysis of disordered low-Z materials are presented. Several scientifically and technologically important classes of disordered low-Z materials such as small and large organic molecules, graphitic powders, polymers and liquids are intentionally explored to certify the technique's performance. Resu...