CASINO manual - Theory of Condensed Matter
CASINO manual - Theory of Condensed Matter
CASINO manual - Theory of Condensed Matter
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not the case the defaults can be changed with the --chome and --ehome flags. Fine-grained control<br />
over parallelism in pwscf is done by defining the number <strong>of</strong> images, pools, task groups and linear<br />
algebra groups (see the Espresso documentation); these may be specified with the --image, --npool,<br />
--ntg and --ndiag flags to runpwscf.<br />
Note that if your casino arch file defines a command for running casino and pwscf (such as<br />
SCRIPT RUN: mpirun -np &NPROC& &BINARY&), then it must include a tag &BINARY ARGS& following<br />
the &BINARY& tag. This is because the pwscf executable takes command line arguments such as<br />
-pw2casino, -npool etc., which are not required by casino. For this reason an arch file which works<br />
for casino may not necessarily work for pwscf without this modification. To check this on a batch<br />
machine, type ‘runpwscf --qmc --check-only’ and examine the resulting ‘pw.x’ batch file. If the<br />
line containing, e.g., the mpirun command above does not have ‘-pw2casino’ following ‘pw.x’, then<br />
you will need to add &BINARY ARGS& to your arch file.<br />
The interface between pwscf and casino is provided through a file with a standard format containing<br />
geometry, basis set and orbital coefficients. For SCF calculations, the name <strong>of</strong> this file may be<br />
pwfn.data, bwfn.data or bwfn.data.b1 depending on user requests (see below). If the files are<br />
produced from an MD run, the files have a suffix ‘.1’, ‘.2’, ‘.3’, etc., corresponding to the sequence <strong>of</strong><br />
time steps.<br />
casino support is implemented by three routines in the PW directory <strong>of</strong> the espresso distribution:<br />
• pw2casino.f90: the main routine,<br />
• pw2casino write.f90: writes the casino xwfn.data file in various formats,<br />
• pw2blip.f90: does the plane wave to blip conversion, if requested.<br />
Relevant behaviour <strong>of</strong> pwscf may be modified through an optional auxiliary input file, named<br />
pw2casino.dat (see below).<br />
In some versions prior to 4.3, this functionality was provided through separate post-processing utilities<br />
available in the PP directory: these are no longer supported. For QMC-MD runs, pwscf, etc.,<br />
previously needed to be ‘patched’ using the patch script PP/pw2casino-MDloop.sh; this is no longer<br />
necessary.<br />
Note that ‘twist-averaged’ calculations may be done with pwscf/casino using the twistav pwscf<br />
script. See Sec. 28.3.4.<br />
How to generate xwfn.data files with PWSCF<br />
Use the ‘-pw2casino’ option when invoking pw.x, e.g.:<br />
pw.x -pw2casino < input file > output file<br />
The xfwn.data file will then be generated automatically.<br />
If running using the supplied runpwscf script, then one would type (with assumed in.pwscf and<br />
out.pwscf i/o files):<br />
runpwscf --qmc OR runpwscf -w<br />
On parallel machines, one could type, e.g.,<br />
runpwscf --qmc -p 128<br />
to run the calculation on 128 cores, or whatever.<br />
pwscf is capable <strong>of</strong> doing the plane wave to blip conversion (see Sec. 9) directly (the ‘blip’ utility<br />
provided in the casino distribution is not required) and so by default, pwscf produces the ‘binary<br />
blip wave function’ file bwfn.data.b1.<br />
Various options may be modified by providing a file ‘pw2casino.dat’ with the following format:<br />
&inputpp<br />
blip_convert=.true.<br />
blip_binary=.true.<br />
blip_single_prec=.false.<br />
blip_multiplicity=1.d0<br />
n_points_for_test=0<br />
/<br />
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