<div dir="ltr"><div class="content">Hello <br><br>I
am calculating bader charges from a cube file for hexagonal GaN bulk
system. The Ga and N layers in this compound are in the form of :
ABA'B'ABA'B'..... where the difference between A and A' layers is that
they are slightly shifted laterally with respect to each other.
Similarly, the B and B' layers. First, I have generated a charge density
cube file by doing post-processing of the wavefunctions collected from
the scf calculation of bulk 2x2x2 GaN system in Quantum Espresso. Then I
ran the bader code for the cube file to get the charges. The k-point
grid I used is 12x12x12 .<br><br>The total charge of the system comes
out to be correct (the expected valence charge of the system). Also, the
charges on atoms of the same layer are same. But the problem is that
the charges on Ga atoms of layers A and A' (and also charges on N atoms
of layers B and B') are not same. This is a bulk system and all the Ga
atoms are in same chemical environment. They are tetrahedrally bonded to
4 N atoms (and same is true for N atoms, N atoms in layers B and B' are
tetrahedrally bonded to 4 Ga atoms). So, I expected that the charges on
all the Ga atoms in this bulk system should be same. Can someone please
tell me what I am missing? <br>The z-valence in the pseudopotential file for Ga and N are 13 and 5 respectively.<br><br>Here is the content from ACF.dat file :<br><br> # X Y Z CHARGE MIN DIST ATOMIC VOL<br> --------------------------------------------------------------------------------<br> 1 18.2640 10.5444 19.7982 11.4266 1.5237 66.6395<br> 2 15.2200 5.2722 19.7982 11.4265 1.5237 66.6358<br> 3 12.1760 10.5444 19.7982 11.4266 1.5237 66.6395<br> 4 9.1320 5.2722 19.7982 11.4266 1.5237 66.6395<br> 5 18.2640 10.5444 3.7320 6.5809 1.7181 92.3652<br> 6 15.2200 5.2722 3.7320 6.5809 1.7181 92.3652<br> 7 12.1760 10.5444 3.7320 6.5809 1.7181 92.3652<br> 8 9.1320 5.2722 3.7320 6.5809 1.7181 92.3652<br> 9 3.0428 1.7567 4.9495 11.3747 1.5089 64.9901<br> 10 9.1308 1.7567 4.9495 11.3747 1.5089 64.9901<br> 11 6.0868 7.0289 4.9495 11.3747 1.5088 64.9901<br> 12 12.1748 7.0289 4.9495 11.3747 1.5089 64.9901<br> 13 3.0428 1.7567 8.6815 6.6179 1.7392 93.7406<br> 14 9.1308 1.7567 8.6815 6.6179 1.7393 93.7406<br> 15 6.0868 7.0289 8.6815 6.6179 1.7392 93.7461<br> 16 12.1748 7.0289 8.6815 6.6179 1.7392 93.7461<br> 17 18.2640 10.5444 9.8991 11.4265 1.5237 66.6339<br> 18 15.2200 5.2722 9.8991 11.4265 1.5237 66.6358<br> 19 12.1760 10.5444 9.8991 11.4265 1.5237 66.6339<br> 20 9.1320 5.2722 9.8991 11.4265 1.5237 66.6358<br> 21 18.2640 10.5444 13.6310 6.5809 1.7181 92.3652<br> 22 15.2200 5.2722 13.6310 6.5809 1.7181 92.3652<br> 23 12.1760 10.5444 13.6310 6.5809 1.7181 92.3652<br> 24 9.1320 5.2722 13.6310 6.5809 1.7181 92.3652<br> 25 3.0428 1.7567 14.8486 11.3747 1.5089 64.9901<br> 26 9.1308 1.7567 14.8486 11.3747 1.5089 64.9901<br> 27 6.0868 7.0289 14.8486 11.3747 1.5088 64.9901<br> 28 12.1748 7.0289 14.8486 11.3747 1.5089 64.9901<br> 29 3.0428 1.7567 18.5806 6.6179 1.7392 93.7424<br> 30 9.1308 1.7567 18.5806 6.6178 1.7393 93.7388<br> 31 6.0868 7.0289 18.5806 6.6178 1.7392 93.7388<br> 32 12.1748 7.0289 18.5806 6.6178 1.7392 93.7388<br> --------------------------------------------------------------------------------<br> VACUUM CHARGE: 0.0000<br> VACUUM VOLUME: 0.0000<br> NUMBER OF ELECTRONS: 288.0005<br><br>I
expected that the charges on Ga atoms having numbers 1,2,3,4 ;
9,10,11,12 ; 17,18,19,20 ; 25,26,27,28 should all be same. Same
should be true for N atoms. <br><br><br>Thank you in advance.<br>Manjusha<br>IIT Kanpur, India</div>
<br></div>