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understanding the PROCAR file

Posted: Wed Sep 19, 2012 6:10 pm
by gjenness
I'm trying to figure out which bands correspond to either bonding or anti-bonding states --- note that I don't really need a full COOP/COHP curve, I just need a qualitative feel for which is which. I think I can get this information from examining the PROCAR file (generated with LORBIT=12), as that contains the phase factors (amongst other things).

As a simple example, lets take a look at the PROCAR for CO in the gas-phase, with the molecular axis aligned along the z-axis. According to the MO diagram, what we should see is 4 bands below the Fermi level, corresponding to the occupied orbitals --- a 2sigma, a 2sigma*, a doubly degenerate 1pi, and a 3sigma. So if we look at the first two bands in the PROCAR file, we get the following.

band 1 # energy -28.94865556 # occ. 2.00000000

ion s py pz px dxy dyz dz2 dxz dx2 tot
1 0.160 0.000 0.124 0.000 0.000 0.000 0.000 0.000 0.000 0.284
2 0.658 0.000 0.097 0.000 0.000 0.000 0.000 0.000 0.000 0.755
tot 0.818 0.000 0.221 0.000 0.000 0.000 0.000 0.000 0.000 1.039

ion s py pz px dxy dyz dz2 dxz dx2
1 -0.980 0.000 -0.862 0.000 0.000 0.000 0.000 0.000 0.000
1 -0.124 0.000 -0.110 0.000 0.000 0.000 0.000 0.000 0.000
2 -1.716 0.000 0.679 0.000 0.000 0.000 0.000 0.000 0.000
2 -0.218 0.000 0.086 0.000 0.000 0.000 0.000 0.000 0.000


band 2 # energy -13.81786013 # occ. 2.00000000

ion s py pz px dxy dyz dz2 dxz dx2 tot
1 0.190 0.000 0.017 0.000 0.000 0.000 0.000 0.000 0.000 0.207
2 0.168 0.000 0.445 0.000 0.000 0.000 0.000 0.000 0.000 0.613
tot 0.357 0.000 0.463 0.000 0.000 0.000 0.000 0.000 0.000 0.820

ion s py pz px dxy dyz dz2 dxz dx2
1 1.180 0.000 0.379 0.000 0.000 0.000 0.000 0.000 0.000
1 0.147 0.000 0.047 0.000 0.000 0.000 0.000 0.000 0.000
2 -0.937 0.000 -1.512 0.000 0.000 0.000 0.000 0.000 0.000
2 -0.117 0.000 -0.188 0.000 0.000 0.000 0.000 0.000 0.000


Now as I understand it, the first table (highlighted in blue) for each band is some sort of charge/occupancy, and the second table (highlighted in red) corresponds to the phase factors. In addition, the table with the phase factors, the first row for each ion corresponds to the real part, and the second row corresponds to the imaginary part.

Using a simple COOP picture, we know that if there is a positive overlap, then the band is bonding, but if the overlap is negative, the band is anti-bonding. My question is, how can we use the phase factors in PROCAR file to determine, at least from a qualitative standpoint, which bands are bonding and anti-bonding?

Re: understanding the PROCAR file

Posted: Thu Sep 12, 2024 7:35 am
by support_vasp

Hi,

We're sorry that we didn’t answer your question. This does not live up to the quality of support that we aim to provide. The team has since expanded. If we can still help with your problem, please ask again in a new post, linking to this one, and we will answer as quickly as possible.

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