Surface of maximum charge density

[Vishal]

[attachment=0]bader_illustrator.jpg[/attachment]

Hello Everyone,

The attached image shows the image of the surface of maximum charge density for O2 molecule. My question is, 1. Is it the same as bader surface 2.How to trace this curve given charge density file for O2 molecule

[graeme]

The Bader surfaces contain minima in the charge density along the direction perpendicular to the surface. In principle, I guess there should be surfaces for which the charge density is maximum along the surface normal. These would pass through the atomic cores. I have not seen these surfaces calculated before, but people do often traces curves in these surfaces. For example, the maximal line drawn in your illustration can be generalized to 3D to a curve that connects the atomic centers to bond critical points. In this way, such curves can be helpful for understanding bonding topology.

If you want to play around with it, you could change the sign of the charge density file and use our Bader code to find them. You may have to do something like MaxVal-CHGCAR so that it stays positive, but anyway, you probably get the idea.

[Vishal]

Dear Professor Graeme,

Thanks for your reply and advice. I still do not get why charge density is maximum near the atomic cores. I would be really thankful if you explain that.

[graeme]

The solution to the Schrodinger equation for a 1/r potential has a cusp (maximum) at the nuclei - just as in your illustration.

[Vishal]

Dear Professor Graeme,

I believe the above illustration is a 2-d curve where charge density peaks along different directions with respect to the two atoms. Or is it a graph where y-axis is charge density maxima and x-axis is distance. I'm asking this because you said the maxima curve should pass through the nuclei. But it doesn't seem in this case. Please Clarify.

Thank You

[graeme]

Ah, no, it is a 1d plot of charge density (y-axis) vs distance (x-axis). The peaks in the charge density correspond to the location of the atomic centers (blue circles).