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Charge density in .dden.cube
Date: 2015/05/28 23:08
Name: Artem Pulkin


Apparently I took a sum of values on the grid in a aforementioned file. The result I obtained is 0.0014 whatever-units-used while the minimum and maximum values on this grid are -0.03 and 0.019 correspondingly.

I would expect the sum to be zero in a PBC DFT calculation. Why it is not so? Is it more reliable to take the sum of Mulliken populations from the textual output?


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Re: Charge density in .dden.cube ( No.1 )
Date: 2015/06/08 15:04
Name: T. Ozaki


I also did a similar analysis using Cdia.dat stored in "work" directory,
and obtained the following result:

150 0.00038020 0.02169571 0.0000082487
240 0.00047123 0.01020800 0.0000048103
400 0.00045722 0.00430650 0.0000019690
600 0.00058173 0.00271196 0.0000015776


#1 scf.energycutoff
#2 sum
#3 GridVol
#4 #2*#3 = sum*GridVol

It turns out that the residual charge (#4) is about 10^{-6} electron per unit cell,
which can be attributed to error in the numerical integration.

Since Mulliken populations are free from such an error, you may obtain a smaller number
when you sum up them.




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