#!/bin/sh

# run from directory where this script is
cd `echo $0 | sed 's/\(.*\)\/.*/\1/'` # extract pathname
EXAMPLE_DIR=`pwd`

# check whether ECHO has the -e option
if test "`echo -e`" = "-e" ; then ECHO=echo ; else ECHO="echo -e" ; fi

$ECHO
$ECHO "$EXAMPLE_DIR : starting"
$ECHO
$ECHO "This example shows how to use pw.x and ph.x to calculate dynamic"
$ECHO "polarizability of methane molecule "

# set the needed environment variables
. ../../../environment_variables

# required executables and pseudopotentials
BIN_LIST="pw.x ph.x"
PSEUDO_LIST="C.pz-vbc.UPF H.pz-vbc.UPF"

$ECHO
$ECHO "  executables directory: $BIN_DIR"
$ECHO "  pseudo directory:      $PSEUDO_DIR"
$ECHO "  temporary directory:   $TMP_DIR"
$ECHO
$ECHO "  checking that needed directories and files exist...\c"

# check for directories
for DIR in "$BIN_DIR" "$PSEUDO_DIR" ; do
    if test ! -d $DIR ; then
        $ECHO
        $ECHO "ERROR: $DIR not existent or not a directory"
        $ECHO "Aborting"
        exit 1
    fi
done
for DIR in "$TMP_DIR" "$EXAMPLE_DIR/results" ; do
    if test ! -d $DIR ; then
        mkdir $DIR
    fi
done
cd $EXAMPLE_DIR/results

# check for executables
for FILE in $BIN_LIST ; do
    if test ! -x $BIN_DIR/$FILE ; then
        $ECHO
        $ECHO "ERROR: $BIN_DIR/$FILE not existent or not executable"
        $ECHO "Aborting"
        exit 1
    fi
done

# check for pseudopotentials
for FILE in $PSEUDO_LIST ; do
    if test ! -r $PSEUDO_DIR/$FILE ; then
       $ECHO
       $ECHO "Downloading $FILE to $PSEUDO_DIR...\c"
            $WGET $PSEUDO_DIR/$FILE $NETWORK_PSEUDO/$FILE 2> /dev/null
    fi
    if test $? != 0; then
        $ECHO
        $ECHO "ERROR: $PSEUDO_DIR/$FILE not existent or not readable"
        $ECHO "Aborting"
        exit 1
    fi
done
$ECHO " done"

# how to run executables
PW_COMMAND="$PARA_PREFIX $BIN_DIR/pw.x $PARA_POSTFIX"
PH_COMMAND="$PARA_PREFIX $BIN_DIR/ph.x $PARA_POSTFIX"
$ECHO
$ECHO "  running pw.x as: $PW_COMMAND"
$ECHO "  running ph.x as: $PH_COMMAND"
$ECHO

# clean TMP_DIR
$ECHO "  cleaning $TMP_DIR...\c"
rm -rf $TMP_DIR/ch4*
rm -rf $TMP_DIR/_ph0/ch4*
$ECHO " done"


# self-consistent calculation
chbl=1.10           #C-H bond length in CH4
bohr=0.529177
n=5
lc=$(echo "scale=5; $n * $chbl / $bohr" | bc)  # latt. const. in a.u.
pos=$(echo "scale=5; 1.0/$n/sqrt(3)" | bc )
ecut=40
#
cat > ch4.scf.in << EOF
&control
    calculation='relax'
    prefix='ch4',
    restart_mode='from_scratch',
    pseudo_dir = '$PSEUDO_DIR/',
    outdir='$TMP_DIR/'
 /
 &system
    ibrav=  1, celldm(1) = $lc, nat=  5, ntyp= 2,
    ecutwfc = $ecut
 /
 &electrons
 /
 &ions
 /
ATOMIC_SPECIES
 C  12.0107   C.pz-vbc.UPF
 H  1.00794   H.pz-vbc.UPF
ATOMIC_POSITIONS alat
 C  0.00  0.00  0.00
 H  $pos   $pos   $pos
 H  $pos  -$pos  -$pos
 H -$pos  -$pos   $pos
 H -$pos   $pos  -$pos
K_POINTS
   1
   0.00 0.00 0.00 1.0
EOF
#
$ECHO "  running the scf calculation...\c"
$PW_COMMAND < ch4.scf.in > ch4.scf.out
check_failure $?
$ECHO " done"
#
# dynamic polarizability calculation
#
cat > ch4.fpol.in << EOF

&inputph
  tr2_ph=1.0d-14,
  prefix='ch4',
  epsil=.true.,
  trans=.false.,
  fpol=.true.,
  amass(1)=12.0107,
  amass(2)=1.00794,
  outdir='$TMP_DIR/',
  fildyn='ch4.dynG',
 /
0.0 0.0 0.0

FREQUENCIES
 2
 0.0d0
 1.5d0
EOF
#
$ECHO "  running the dynamic polarizability calculation ...\c"
$PH_COMMAND < ch4.fpol.in > ch4.fpol.out
check_failure $?
$ECHO " done"

$ECHO
$ECHO "$EXAMPLE_DIR : done"
