CASINO manual - Theory of Condensed Matter

7.3 Basic input file: input
The file input contains all the parameters needed to control the QMC calculation. A complete list
of the input parameters is given below. Further details, including default values, may be found by
using the casinohelp utility. Type casinohelp all to get a list of all keywords that casino knows
about, or casinohelp keyword for detailed help on a particular keyword. Type casinohelp search text
to search for the string text in all the keyword descriptions. Create a blank file containing the keyword
input example and type runqmc—this will create a sample input file containing all valid keywords
and their default values in the correct format.
The input file is meant to be very flexible and the list of understood keywords can vary with time
without breaking anything. The input file is based on an early version of the electronic-structure
data format (ESDF) developed for the castep code. The main points are summarized below. See
the comments at the top of the esdf.f90 module for more information.
• Each line is of the form ‘keyword : value’. There must be a space either side of the colon.
• The parameters are divided into types: ‘string’/‘integer’/‘single’/‘double’/‘physical’/‘boolean’.
Variables of ‘physical’ type must be supplied with a unit, such as ‘hartree’, ‘eV’, ‘rydberg’ or
‘Joules/Megaparsec’. All reasonable physical units are understood.
• The parameter names are case-insensitive (e.g., RunType is equivalent to runtype) and
punctuation-insensitive (run type is equivalent to run-type and runtype). Punctuation characters
are ‘.’, ‘ ’ and ‘-’.
• Some of the parameters are of ‘block’ type, which means that multiple parameters must be
supplied, which may be spread over several lines. See, e.g., ‘qmc plot’.
Note that the input file is never written to by casino (though there are a couple of utilities, such as
the runqmcmd script, which temporarily manipulate it). Files generated by other codes, which may
contain large amounts of data, are not included in input.
7.3.1 List of current input keywords
Here is the current list of the input parameters in alphabetical order (a list of some older keywords
is given after this). Note that the casinohelp facility is always up to date (it runs casino to find out
what it knows about)—but this manual may not be.
ALIMIT (Real) Parameter required by DMC drift-velocity- and energy-limiting schemes when
limdmc=2. A value of 1 (the default) is generally appropriate. The DMC energy is insensitive
to the precise value of alimit. alimit is ignored if nucleus gf mods is set to T. See Sec.
13.5.
ALLOW AE PPOTS (Logical) If a user runs casino with pseudopotentials for some ions but not
others, the usual reason is that he or she has forgotten to provide a pseudopotential. Hence
casino stops with an error. However, some users may wish to use the bare Coulomb potential
for e.g. hydrogen ions, while other ions are represented by pseudopotentials. In this case,
allow ae ppots should be set to T.
ALLOW NOCHI ATOMS (Logical) If this keyword is set to T then casino will issue a warning
message when some atoms are not included in any sets of χ or f terms in the Jastrow factor and
µ and Φ terms in the backflow function. Otherwise, casino halts with an error if some atoms
are not included in these terms.
ALLOW SLAVE WRITE (Logical) The ALLOW SLAVE WRITE flag can be used to allow/disallow
slave node output to the main output file. The default is to allow it. The ability
to turn this off can be useful when you’re running on a million cores.
ATOM BASIS TYPE (Text) This selects the basis set in which the atom-centred orbitals are
expanded, thus choosing which file to read the orbitals from. Possible values are:
‘none’ (default): no atoms are present, so no externally generated orbitals are read in;
‘plane-wave’: use a plane-wave basis set; the orbitals are read in from pwfn.data;
‘gaussian’: use a Gaussian basis set; the orbitals are read in from gwfn.data;
34