Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Real-space electronic-structure calculations with timesaving double-grid
  technique   We present a set of efficient techniques in first-principles
electronic-structure calculations utilizing the real-space finite-difference
method. These techniques greatly reduce the overhead for performing integrals
that involve norm-conserving pseudopotentials, solving Poisson equations, and
treating models which have specific periodicities, while keeping a high degree
of accuracy. Since real-space methods are inherently local, they have a lot of
advantages in applicability and flexibility compared with the conventional
plane-wave approach, and promise to be well suited for large and accurate {\it
ab initio} calculations. In order to demonstrate the potential power of these
techniques, we present several applications for electronic structure
calculations of atoms, molecules and a helical nanotube.

11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con