# [Pw_forum] About full Fully-Relativistic Calculation of GaAs

Fengjie Ma fengjie.ma at gmail.com
Tue Jun 20 14:58:15 CEST 2006

```Dear all:
When I use espresso-3.1 to generate full relativistic pseudopotentials of
Ga and As, I find some problems:
1.  I choose nlcc=.False., and get the pseudopotentials of Ga and
As.  However, when I use them to calculate the band structure of GaAs,
I find that I must write both  lspinorb=.true. and
noncolin=.true. in the input file. If not, the band split at Gamma point
will not appear. Why?
2.  Use the pseudopotntials, whether choose  nlcc=.true. or not,  the
gap between valence band and conduct band becomes only 0.6 eV.
I know that should be 1.4eV in GaAs, Why?
( I also re-calculate with changing the matching radius, but get the
same problems)

Could anyone tell me, is there any critical mistakes  and how should I
solve this problem?

Ma Fengjie

------------------------------------------------------------------------
&input
title='As',
zed=33.,
rel=2,
rlderiv=2.50,
eminld=-4.0,
emaxld=4.0,
deld=0.02,
nld=5,
iswitch=3,
config='[Ar] 3d10 4s2 4p3 4d-1'
dft='LDA',
&
&inputp
pseudotype=2,
lloc=2,
nlcc =.true.,
file_pseudopw='Asrel.RRKJ3',
&
5
4S  1  0  2.00  0.00  2.20  2.20  0.50
4P  2  1  2.00  0.00  2.20  2.20  0.50
4P  2  1  1.00  0.00  2.20  2.20  1.50
4D  3  2  0.00  0.05  2.30  2.30  1.50
4D  3  2  0.00  0.05  2.30  2.30  2.50
--------------------------------------------------------------------------------
&input
title='Ga',
zed=31.,
rel=2,
rlderiv=2.50,
eminld=-4.0,
emaxld=4.0,
deld=0.02,
nld=5,
iswitch=3,
config='[Ar] 3d10 4s2 4p0.33 4p0.67 4d-1'
dft='LDA',
&
&inputp
pseudotype=2,
lloc=2,
nlcc =.true.,
file_pseudopw='Ga.RRKJ3',
&
5
4S  1  0  2.00  0.00  2.40  2.40  0.50
4P  2  1  0.33  0.00  1.60  1.60  0.50
4P  2  1  0.67  0.00  1.60  1.60  1.50
4D  3  2  0.00  0.05  2.70  2.70  1.50
4D  3  2  0.00  0.05  2.70  2.70  2.50
--------------------------------------------------------------------------------
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```