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[Zeila Zanolli <zanolli@pcpm.ucl.ac.be>]

Dear Wang,

In the study of InAs there are, indeed, problems in getting the correct occupation of the valence/conduction states at the LDA level of the calculation.

Then, if the LDA occupations are too far from what they should be, the GW calculation cannot do that much, and this is why even the GW calculated gap is far from what it should be.

The problem in InAs are mostly due to the "d" electronic states of In.  You can find more info on this topic in the paper 

PhysRevB vol 75 (2007) 245121

"Model GW band structure of InAs and GaAs in the wurtzite phase"

where results for InAs zincblende are reported as well.

By the way, which pseudopotential are you using? Are you including the 'semicore' states? 

The best would be to use a pseudo for In that includes the 4d, 4s and 4p among the valence electrons...

Another thing, which is the LDA gap you find when using the metallic occupation?

All the best,

Zeila

On 30 Mar 2008, at 19:26, wxw079000@utdallas.edu wrote:

Dear All,

I tried to calculate the InAs band structure using GW correction. The default systme is a semiconductor. The InAs

 band gap is 0.0 eV from LDA calculaiton and the GW correction(5.4.4 Version) is about 0.007 eV, which is very 

small comparing the experimental value 0.53 eV. Then, I tried to treat the system as a metal, i.e, occopt=7 and 

tsmear value =0.01(also 0.04,0.05,0.1,0.5), the GW correction is around 0.1 eV.

The following is my input and output file for the GW calculation. Is there any kind person help me with this issue?

Thanks in advance,

Best wishes,

Weichao,Wang

Input file

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

ndtset      4

kptopt   1            # Option for the automatic generation of k points

ngkpt    6 6 6        # Density of k points

nkpt1    28

nshiftk1  4

shiftk1  0.5 0.5 0.5  # This grid is the most economical

         0.5 0.0 0.0

         0.0 0.5 0.0

         0.0 0.0 0.5

prtden1  1         # Print out density

# Dataset2: calculation of kss file

nkpt2    44             # A set of 19 k-points containing Gamma

nshiftk2  4

shiftk2  0.0 0.0 0.0  # This grid contains the Gamma point

         0.0 0.5 0.5

         0.5 0.0 0.5

         0.5 0.5 0.0

istwfk2  44*1                    # Option needed for Gamma

iscf2    -2             # Non self-consistent calculation

getden2  -1             # Read previous density file

nband2   10

nbandkss2 100        # Number of bands to store in KSS file

# Dataset3: Calculation of the screening (epsilon^-1 matrix)

optdriver3  3        # Screening calculation

getkss3     -1       # Obtain KSS file from previous dataset

nband3     150       # Bands to be used in the screening calculation

ecutwfn3    6.0      # Planewaves to be used to represent the wavefunctions

ecuteps3    6.0      # Dimension of the screening matrix

ppmfrq3    16.7 eV  # Imaginary frequency where to calculate the screening

# Dataset4: Calculation of the Self-Energy matrix elements (GW corrections)

optdriver4  4        # Self-Energy calculation

getkss4     -2       # Obtain KSS file from dataset 1

getscr4     -1       # Obtain SCR file from previous dataset

nband4      150      # Bands to be used in the Self-Energy calculation

ecutwfn4    6.0      # Planewaves to be used to represent the wavefunctions

ecutsigx4    6.0      # Dimension of the G sum in Sigma_x

                     # (the dimension in Sigma_c is controlled by npweps)

nkptgw4      1                # number of k-point where to calculate the GW correction

kptgw4                       # k-points

  0.000    0.000    0.000    # (Gamma)

bdgw4       4  5             # calculate GW corrections for bands from 4 to 5

# Definition of the unit cell: fcc

acell  3*11.434        # This is equivalent to   10.217 10.217 10.217

rprim  0.0  0.5  0.5   # FCC primitive vectors (to be scaled by acell)

       0.5  0.0  0.5

       0.5  0.5  0.0

# Definition of the atom types

ntypat  2         # There two types of atom

znucl 49 33       # The keyword "znucl" refers to the atomic number of the 

                  # possible type(s) of atom. The pseudopotential(s) 

                  # mentioned in the "files" file must correspond

                  # to the type(s) of atom. Here, the only type is Silicon.

# Definition of the atoms

natom 2           # There are two atoms

typat  1 2        # They both are of type 1, that is, Silicon.

xred              # Reduced coordinate of atoms

      0.0  0.0  0.0

      0.25 0.25 0.25

ecut 16.0          

symmorphi 0

# Definition of the SCF procedure

nstep   30        # Maximal number of SCF cycles

diemac  16.0      # Although this is not mandatory, it is worth to

                  # precondition the SCF cycle. The model dielectric

                  # function used as the standard preconditioner

                 # is described in the "dielng" input variable section.

tolwfr  1.0d-10

  iscf 5

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Dr. Zeila Zanolli

Université Catholique de Louvain (UCL)

Unité Physico-Chimie et de Physique des Matériaux (PCPM) 

Place Croix du Sud, 1 (Boltzmann)

B-1348 Louvain-la-Neuve, Belgium

Phone: +32 (0)10 47 3501 

Mobile: +32 (0)487 556699

Fax: +32 (0)10 47 3452

e-mail: zeila.zanolli@uclouvain.be

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