[Pw_forum] Questions about nscf calculation

[孙阳]

Dear all users:

I have a problem regarding the non-selfconsistent calculation. My
system involves a metallic slab
under an external electric filed with a magnitude of 1.0V/A,
equivalently about 0.02 au. the
self consistent calculation was OK, and I compare the electric field
with the screening charges. It
gives me a satiesfied result. Then in order to extract the local
density of states, I did the non-self
consistent calculation with fine K-point mesh, and then do the local
density of states.However, It
gives quite astonishing result. Not only the shape of the local
density of states was significantly
changed from one to the other on the edges of the slab, but also
overestimated the screening charges.
I went back and used the wave functions generated by the scf
calculations to do the local density
of states. It also have a huge difference with the one using the nscf
calculation. I wonder where the
problem is. Following is the input for nscf calculation.

   &control
    calculation='nscf'
    restart_mode='from_scratch',
    wf_collect = .true.
    pseudo_dir = '$PSEUDO_DIR/',
    outdir='$TMP_DIR/'
    prefix='Pd'
 /
 &system

    ibrav = 6,
    celldm(1) =  5.18564536158
    celldm(3) = 8.48528137424
    nat = 7
    nspin = 2
    starting_magnetization = 0.5
    ntyp = 1
    ecutwfc = 100.0,
    ecutrho = 800.0,
    occupations='smearing',
    degauss= 0.01
    edir = 3
    emaxpos=0.4
    eopreg=0.2
    eamp = -0.01944
    nosym = .true.

 /
  &electrons
    conv_thr = 1.0e-8
    mixing_beta = 0.7
    startingpot='file'
    startingwfc='atomic'
    mixing_mode='local-TF'
    mixing_beta = 0.1
    mixing_ndim = 12



/
 &ions
 /

ATOMIC_SPECIES
Pd 1.0 Pd.pz-nd-rrkjus.UPF

ATOMIC_POSITIONS (alat)
Pd       0.500000000   0.500000000  -2.107651139
Pd       0.000000000   0.000000000  -1.412052059
Pd       0.500000000   0.500000000  -0.706700124
Pd       0.000000000   0.000000000   0.000000010
Pd       0.500000000   0.500000000   0.706700124
Pd       0.000000000   0.000000000   1.412052059
Pd       0.500000000   0.500000000   2.107651139


K_POINTS (automatic)
 16 16 1  0 0 0

EOF
echo
echo "#######################################################################"
echo Running PW.x for the nscf calculation ...
$PW_COMMAND < nscf.in  > nscf.out
echo done


-- 
University of Nebraska at Lincoln