#!/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 total energy of an isolated"
$ECHO "atom in a supercell with fixed occupations."
$ECHO "Two examples: LDA energy of Al and sigma-GGA energy of O."

# set the needed environment variables
. ../environment_variables

# required executables and pseudopotentials
BIN_LIST="pw.x"
PSEUDO_LIST=" Al.vbc.UPF O.pbe-rrkjus.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 "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
 
# clean TMP_DIR
$ECHO "  cleaning $TMP_DIR...\c"
rm -rf $TMP_DIR/*
$ECHO " done"

# self-consistent calculation for isolated Al atom
cat > al.in << EOF
 &control
    calculation='scf',
    restart_mode='from_scratch',
    pseudo_dir='$PSEUDO_DIR/'
    outdir='$TMP_DIR/'
 /
 &system
   ibrav=1,
   celldm(1)=20.0,
   nat=1,
   ntyp=1,
   nbnd=6,
   nosym=.true.,
   ecutwfc=15.0,
   occupations='from_input',
 /
 &electrons
   mixing_beta=0.35,
   conv_thr=1.0E-8,
 /
ATOMIC_SPECIES
Al     26.98154    Al.vbc.UPF
ATOMIC_POSITIONS   
Al      0.0000000000   0.0000000000     0.000
K_POINTS  AUTOMATIC
1   1   1   0   0   0
OCCUPATIONS
2.0 0.3333333333333 0.333333333333 0.3333333333333 0.0 0.0 
EOF
$ECHO "  running self-consistent calculation for Al atom...\c"
$PW_COMMAND < al.in > al.out
$ECHO " done"

# self consistent calculation for the spin polarized O atom
cat > O.in << EOF
 &control
    calculation='scf',
    restart_mode='from_scratch',
    pseudo_dir='$PSEUDO_DIR/'
    outdir='$TMP_DIR/'
 /
 &system
   ibrav=1,
   celldm(1)=14.0,
   nat=1,
   ntyp=1,
   nbnd=6,
   nosym=.true.,
   ecutwfc=27.0,
   ecutrho=216.0,
   occupations='from_input',
   nspin=2,
   starting_magnetization(1)=0.5d0,
 /
 &electrons
   mixing_beta=0.25,
   conv_thr=1.0E-8,
 /
ATOMIC_SPECIES
O     15.99994   O.pbe-rrkjus.UPF
ATOMIC_POSITIONS   
O   0.000000000   0.000000000   0.000000000  
K_POINTS AUTOMATIC
1   1   1   0   0   0
OCCUPATIONS
1.0 1.0 1.0 1.0 0.0 0.0 
1.0 0.33333333333 0.33333333333 0.33333333333 0.0 0.0 
EOF
$ECHO "  running calculation for O atom...\c"
$PW_COMMAND < O.in > O.out
$ECHO " done"

#
cat > O_gamma.in << EOF
 &control
    calculation='scf',
    restart_mode='from_scratch',
    pseudo_dir='$PSEUDO_DIR/'
    outdir='$TMP_DIR/'
 /
 &system
   ibrav=1,
   celldm(1)=14.0,
   nat=1,
   ntyp=1,
   nbnd=6,
   nosym=.true.,
   ecutwfc=27.0,
   ecutrho=216.0,
   occupations='from_input',
   nspin=2,
   starting_magnetization(1)=0.5d0,
 /
 &electrons
   mixing_beta=0.25,
   conv_thr=1.0E-8,
 /
ATOMIC_SPECIES
O     15.99994   O.pbe-rrkjus.UPF
ATOMIC_POSITIONS   
O   0.000000000   0.000000000   0.000000000  
K_POINTS (gamma)
OCCUPATIONS
1.0 1.0 1.0 1.0 0.0 0.0 
1.0 0.33333333333 0.33333333333 0.33333333333 0.0 0.0 
EOF
$ECHO "  running calculation for O atom, Gamma-only...\c"
$PW_COMMAND < O_gamma.in > O_gamma.out
$ECHO " done"

$ECHO
$ECHO "$EXAMPLE_DIR: done"