#!/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, turbo_eels.x, and turbo_spectrum.x"
$ECHO "to calculate the electron energy loss spectrum of bulk silicon."

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

# required executables and pseudopotentials
BIN_LIST="pw.x turbo_eels.x turbo_spectrum.x"
PSEUDO_LIST="Si.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
$ECHO " 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 $PARA_POSTFIX"
TURBO_EELS_COMMAND="$PARA_PREFIX $BIN_DIR/turbo_eels.x $PARA_POSTFIX"
TURBO_SPECTRUM_COMMAND="$PARA_PREFIX $BIN_DIR/turbo_spectrum.x $PARA_POSTFIX"
$ECHO
$ECHO "  running pw.x as:             $PW_COMMAND"
$ECHO "  running turbo_eels.x as:     $TURBO_EELS_COMMAND"
$ECHO "  running turbo_spectrum.x as: $TURBO_SPECTRUM_COMMAND"
$ECHO

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

PREFIX='Si'

# self-consistent calculation
cat > $PREFIX.scf.in << EOF
 &control
    calculation='scf'
    restart_mode='from_scratch',
    prefix='$PREFIX'
    pseudo_dir = '$PSEUDO_DIR/'
    outdir='$TMP_DIR/'
 /
 &system
    ibrav = 2,
    celldm(1) = 10.26,
    nat = 2,
    ntyp = 1,
    ecutwfc = 16.0
 /
 &electrons
    conv_thr =  1.0d-10
 /
ATOMIC_SPECIES
Si  28.08  Si.pz-vbc.UPF
ATOMIC_POSITIONS {alat}
Si 0.00 0.00 0.00
Si 0.25 0.25 0.25
K_POINTS {automatic}
3 3 3 1 1 1
EOF
$ECHO "  Running the SCF calculation for $PREFIX..."
$PW_COMMAND < $PREFIX.scf.in > $PREFIX.scf.out
$ECHO " done"


# Perform the linear-response calculation
cat > $PREFIX.tddfpt.in << EOF
 &lr_input
   prefix = '$PREFIX',
   outdir = '$TMP_DIR/',
   restart_step = 250,
   restart = .false.
 /
 &lr_control
   calculator = 'lanczos',
   itermax = 500,
   q1 = 0.866,
   q2 = 0.000,
   q3 = 0.000
 /
EOF
$ECHO "  Running the TDDFPT calculation for $PREFIX..."
$TURBO_EELS_COMMAND < $PREFIX.tddfpt.in > $PREFIX.tddfpt.out
$ECHO " done"


# Perform the postprocessing spectrum calculation
cat > $PREFIX.tddfpt_pp.in << EOF
 &lr_input
   prefix = '$PREFIX',
   outdir = '$TMP_DIR/',
   eels = .true.
   itermax0 = 500,
   itermax  = 10000,
   extrapolation = "osc",
   epsil = 0.035,
   units = 1,
   start = 0.0,
   end   = 50.0,
   increment = 0.01
 /
EOF
$ECHO "  Running the postprocessing spectrum calculation for $PREFIX..."
$TURBO_SPECTRUM_COMMAND < $PREFIX.tddfpt_pp.in > $PREFIX.tddfpt_pp.out
$ECHO " done"
