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small minimum distance

Posted: Sun Dec 23, 2007 7:57 pm
by yello
First, I do a calculation on the CO moleucle based on US-PP (GGA91) using the VASP code. And then I use the bader analysis to get the charge distribution on C and O atoms. The ACF file is as follow:

# X Y Z CHARGE MIN DIST
----------------------------------------------------------------
1 6.8090 7.9761 13.9505 2.2308 0.0536
2 7.9419 7.9533 14.1190 7.7692 1.0473
----------------------------------------------------------------
NUMBER OF ELECTRONS: 10.00000
And I found that the MIN DIST on C is only 0.0536, so is there some error?

Posted: Sun Dec 23, 2007 8:01 pm
by graeme
It looks like you may not have included core charges.

Follow the instructions at http://theory.cm.utexas.edu/bader/vasp.php

and see if the Bader surface are further from the atomic centers.

Posted: Mon Dec 24, 2007 1:31 am
by yello
Thanks!

You mean that the only method to solve this error is using PAW ( not US-PP), isn't it?

I will try it.

Posted: Mon Dec 24, 2007 4:46 am
by graeme
Yes, both PAW and the LAECHG=.TRUE. flag.

Posted: Tue Dec 25, 2007 5:20 am
by yello
I add the core charge to analysis again, the ACF data is :

# X Y Z CHARGE MIN DIST
----------------------------------------------------------------
1 6.8107 7.9761 13.9508 2.8741 0.2951
2 7.9403 7.9533 14.1187 7.1259 0.6892
----------------------------------------------------------------
NUMBER OF ELECTRONS: 10.00000

It looks better now.