ASE Manual Release 3.6.1.2825 CAMd - CampOS Wiki

Restarting from an old Calculation
ASE Manual, Release 3.6.1.2828
If you want to rerun an old SIESTA calculation, made using the ASE interface or not, you can set the fdf tag
UseSaveData to True. This is equivalent to setting both DM.UseSaveDM and MD.UseSaveXV to True, i.e.
it will reuse the the density matrix, and the atomic coordinates (and unit cell) of the previous calculation. Note
that the Siesta jobname (the label keyword in the ASE interface) must be identical to the jobname of the old
calculation.
DftbPlus
Introduction
DftbPlus is a density-functional based tight-binding code using atom centered orbitals. This interface makes it
possible to use DftbPlus as a calculator in ASE. You need to register at DftbPlus site to download the code.
Additionally you need Slater-coster files for the combination of atom types of your system. These can be obtained
at dftb.org.
Environment variables
Set environment variables in your configuration file (what is the directory for the Slater-Koster files and what is
the name of the executable):
• bash:
$ DFTB_PREFIX=/my_disk/my_name/lib/Dftb+sk/mio-0-1/ (an example)
$ DFTB_COMMAND=~/bin/DFTB+/dftb+_s081217.i686-linux (an example)
• csh/tcsh:
$ setenv DFTB_PREFIX /my_disk/my_name/lib/Dftb+sk/mio-0-1/ (an example)
$ setenv DFTB_COMMAND ~/bin/DFTB+/dftb+_s081217.i686-linux (an example)
DftbPlus Calculator
This is a preliminary version of the DftbPlus calculator, so all the DftbPlus features are unfortunately not there.
Use write_dftb=False to use your own ‘dftb_in.hsd’-file with all the flavours you need. In that case ase only
updates the coordinates of the system, otherwise file ‘dftb_in.hsd’ remains intact (see example 2 below). However,
in case of own ‘dftb_in.hsd’ file you need first read in atom position and atom type information of your system for
ase (for instance a xyz-file), see example 2 below.
The atom positions in file ‘dftb_in.hsd’ are updated during ASE geometry optimization.
For the spin polarised calculations this ASE-interface generates parameters with GGA-PBE-spin parameters. If
you need LDA use your own ‘dftb_in.hsd’-file.
Information of periodicity is taken from ase (see example1 below).
For example:
calc = Dftb(label=’o2’,
write_dftb=True,
do_spin_polarized=True,
unpaired_electrons=2.0,
fermi_temperature=100.0,
scc=True)
7.14. Calculators 117