Dear Jaret
You may do two (complementary) things:
1) a Deltarho map. a) Calculation of your whole system and usage of pp.x to
extract the charge density (plot_num=0). b) two separate scf calculations
of the insulator slab and metal slab in the same atomic position of the
previous one and usage of pp.x to extract the charge densities. c) Subtract
the charge densities calculated in b) to the charge densities calculated in a).
If you open the obtained file with xcrysden you can visualize the
charge displacement at the interface (menu tools --> data grid).
Something like this, which has been set up for a molecule/surface system...
export FILEA="molecule+surface"
export INPFILE=$FILEA-cha.inp
export OUTFILE=$FILEA-cha.out
echo " $FILEA"
echo " $INPFILE"
echo " $OUTFILE"
cat > $INPFILE << EOF
&inputpp
prefix = '$FILEA'
outdir = '$TMP_DIR/'
filplot = '$FILEA-cha.dat'
plot_num= 0
/
EOF
$PARA_PREFIX $ESPRESSO/pp.x $PARA_POSTFIX < $INPFILE >> $OUTFILE
export FILEB="molecule"
export INPFILE=$FILEB-cha.inp
export OUTFILE=$FILEB-cha.out
echo " $FILEB"
echo " $INPFILE"
echo " $OUTFILE"
cat > $INPFILE << EOF
&inputpp
prefix = '$FILEB'
outdir = '$TMP_DIR/'
filplot = '$FILEB-cha.dat'
plot_num= 0
/
EOF
$PARA_PREFIX $ESPRESSO/pp.x $PARA_POSTFIX < $INPFILE >> $OUTFILE
export FILEC="surface"
export INPFILE=$FILEC-cha.inp
export OUTFILE=$FILEC-cha.out
echo " $FILEC"
echo " $INPFILE"
echo " $OUTFILE"
cat > $INPFILE << EOF
&inputpp
prefix = '$FILEC'
outdir = '$TMP_DIR/'
filplot = '$FILEC-cha.dat'
plot_num= 0
/
EOF
$PARA_PREFIX $ESPRESSO/pp.x $PARA_POSTFIX < $INPFILE >> $OUTFILE
export FILE="rho-int-$FILEA"
export INPFILE=$FILE.inp
export OUTFILE=$FILE.out
echo " $FILE"
echo " $INPFILE"
echo " $OUTFILE"
cat > $INPFILE << EOF
&inputpp
/
&plot
nfile = 3
filepp(1) = '$FILEA-cha.dat'
weight(1) = 1.0
filepp(2) = '$FILEB-cha.dat'
weight(2) = -1.0
filepp(3) = '$FILEC-cha.dat'
weight(3) = -1.0
iflag = 3
output_format = 5
fileout = '$FILE.plot'
e1(1) =1.0, e1(2)=1.0, e1(3) = 0.0,
e2(1) =0.0, e2(2)=0.0, e2(3) = 1.0,
nx=56, ny=40
/
EOF
$PARA_PREFIX $ESPRESSO/pp.x $PARA_POSTFIX < $INPFILE >> $OUTFILE
2) Use projwfc.x to obtain (Lowdin) atomic charges of your whole system and of
the separate slabs (you may also relax the slabs, in this case, to
account for surface effects). Then you compare the atomic charges to look for
charge displacement. Be aware that there is a spilling parameter at the
end of the projwfc output which indicates how much of your charge density does
not fit into the Lowding atomic partitioning. Your results are
reasonably meaningful only if the spilling parameter is similar for all your
calculations... You may also use the external Bader post processing to
estimate atomic charges, but it requires (to be reliable) PAW or NC
pseudopotentials and hand-adjusted very dense FFT grids. You may like to have a
look here if you want to try
http://theory.cm.utexas.edu/henkelman/code/bader/
HTH
Giuseppe
On Friday, October 23, 2015 06:12:17 AM you wrote:
> Dear Giuseppe,My system is an interface between an insulator and half-metal.
> -Jaret
> AST, USA>Dear mahmoudASU
>
> >First of all sign always your posts to this Forum with name and affiliation,
> >please.
> >
> >There are many ways to calculate charge displacements (Deltarho plots,
> >atomic charge calculations, ...), but their best usage depends on >the kind
> >of charge displacement occurring in your system (molecule-surface
> >interaction, charge transfer affecting dopants or defects in a >semiconductor
> >matrix, ...). Impossible to say more without knowing more...
> >
> >HTH
> >
> >Giuseppe
> >
> >On Wednesday, October 21, 2015 11:42:37 PM Jaret Qi wrote:
> >> Hello QE users,Is there a way to calculate Charge accumulation and
> >> depletion in quantum espresso, if so then how?
> >> -mahmoudASU
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I 00015 - Monterotondo Stazione (RM), Italy
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ResearcherID: F-6308-2012
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