    Generate pulay correction file for a pseudopotential. Usage:

            calcPulay <pspSpec> [<EcutStart>:<dEcut>:<EcutStop>] [<outFile>]

    where

            <pspSpec> specifies the pseudopotential as per the ion-species command
                    in the JDFTx input file (i.e. just the filename for fhi/uspp files).

            <EcutStart>:<dEcut>:<EcutStop> specifies Pulay corrections should be
                    computed from <EcutStart> to <EcutStop> in increments of <dEcut>.
                    Defaults to "5:1:50".

            <outFile> is the path to the computed pulay correction file. Defaults
                    to the pseudopotential filename with the extension replaced by
                    .pulay. (<outFile> must be explicitly specified for .pot/.cpi)

    The details of the computation can be controlled by environment variables:

            boxSize: Periodic image separation of the atoms in bohrs (Default: 20)

            exCorr: Exchange-correlation to use (Default: gga-PBE)

            JDFTx: Path to executable jdftx (or jdftx_gpu) (Default: jdftx)
                    This is required if jdftx is not in $PATH, to use jdftx_gpu, or
                    to use a job management system eg. JDFTx="srun jdftx"

            scratchDir: Temporary directory to store wavefunctions and output files.
                    Must be writeable. Defaults to current directory.