ASE Manual Release 3.6.1.2825 CAMd - CampOS Wiki

ASE Manual, Release 3.6.1.2828
Example 1
Here is an example of how to calculate the total energy for bulk Silicon:
from ase import *
from ase.calculators.abinit import Abinit
a0 = 5.43
bulk = Atoms(’Si2’, [(0, 0, 0),
(0.25, 0.25, 0.25)],
pbc=True)
b = a0 / 2
bulk.set_cell([(0, b, b),
(b, 0, b),
(b, b, 0)], scale_atoms=True)
calc = Abinit(label=’Si’,
nbands=8,
xc=’PBE’,
ecut=50 * Ry,
mix=0.01,
kpts=[10, 10, 10])
bulk.set_calculator(calc)
e = bulk.get_potential_energy()
SIESTA
Introduction
SIESTA is a density-functional theory code for very large systems based on atomic orbital (LCAO) basis sets.
Environment variables
You need to write a script called run_siesta.py containing something like this:
import os
siesta = ’siesta_2.0’
exitcode = os.system(’%s < %s.fdf > %s.txt’ % (siesta, label, label))
The environment variable SIESTA_SCRIPT must point to that file.
A directory containing the pseudopotential files .vps is also needed, and it is to be put in the environment variable
SIESTA_PP_PATH.
Set both environment variables in your shell configuration file:
$ export SIESTA_SCRIPT=$HOME/siesta/run_siesta.py
$ export SIESTA_PP_PATH=$HOME/mypps
SIESTA Calculator
The default parameters are very close to those that the SIESTA Fortran code uses. These are the exceptions:
class siesta.Siesta(label=’siesta’, xc=’LDA’, pulay=5, mix=0.1)
Here is a detailed list of all the keywords for the calculator:
114 Chapter 7. Documentation for modules in ASE