#!/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 calculate the polarization via Berry Phase"
$ECHO "in PbTiO3 (contributed by the Vanderbilt Group in Rutgers University)."

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

# required executables and pseudopotentials
BIN_LIST="pw.x"
PSEUDO_LIST="Pb.pz-d-van.UPF Ti.pz-sp-van_ak.UPF O.pz-van_ak.UPF"

$ECHO
$ECHO "  executables directory: $BIN_DIR"
$ECHO "  pseudo directory:      $PSEUDO_DIR"
$ECHO "  temporary directory:   $TMP_DIR"
$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"
$ECHO
$ECHO "  running pw.x as: $PW_COMMAND"
$ECHO

# self-consistent calculation
cat > chg.in << EOF
 &control
    calculation  = 'scf'
    restart_mode = 'from_scratch'
    pseudo_dir   = '$PSEUDO_DIR/'
    outdir       = '$TMP_DIR/'
 /
 &system
    ibrav=1
    celldm(1)=7.3699,
    nat=5
    ntyp=3
    nbnd=25
    ecutwfc=30.0
    occupations = 'fixed'
    degauss=0.00
 /
 &electrons
    conv_thr = 1e-12,
    mixing_beta=0.3,
 /
ATOMIC_SPECIES
  Pb   207.2      Pb.pz-d-van.UPF
  Ti    47.867    Ti.pz-sp-van_ak.UPF
  O     15.9994   O.pz-van_ak.UPF
ATOMIC_POSITIONS
  Pb    0.000    0.000    0.010
  Ti    0.500    0.500    0.500
  O     0.000    0.500    0.500
  O     0.500    0.500    0.000
  O     0.500    0.000    0.500
K_POINTS {automatic}
  4 4 4 1 1 1
EOF
$ECHO "  running self-consistent calculation in PbTiO3...\c"
$PW_COMMAND < chg.in > chg.out
check_failure $?
$ECHO " done"

# Berry Phase calculation
cat > BP.in << EOF
 &control
    calculation   = 'nscf'
    pseudo_dir    = '$PSEUDO_DIR/'
    outdir        = '$TMP_DIR/'
    lberry        = .true.
    gdir          = 3
    nppstr        = 7
 /
 &system
    ibrav         = 1
    celldm(1)     = 7.3699
    nat           = 5
    ntyp          = 3
    nbnd          = 22
    ecutwfc       = 30.0
    occupations   = 'fixed'
    degauss       = 0.00
 /
 &electrons
    conv_thr      = 1e-5
    mixing_beta   = 0.3
 /
ATOMIC_SPECIES
  Pb   207.2      Pb.pz-d-van.UPF
  Ti    47.867    Ti.pz-sp-van_ak.UPF
  O     15.9994   O.pz-van_ak.UPF
ATOMIC_POSITIONS
  Pb    0.000    0.000    0.010
  Ti    0.500    0.500    0.500
  O     0.000    0.500    0.500
  O     0.500    0.500    0.000
  O     0.500    0.000    0.500
K_POINTS {automatic}
  4 4 7  1 1 1
EOF
$ECHO "  running Berry Phase calculation for PbTiO3...\c"
$PW_COMMAND < BP.in > BP.out
check_failure $?
$ECHO " done"

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


$ECHO
$ECHO "$EXAMPLE_DIR: done"