How to integrate CHGCAR values in Z-direction of a cell?

[skm]

Hi
i asked this query at other forum. But also just found that some similar tool is there in vtst tools as well. So, asking the same here as well, please.

---
i did a CHGCAR file written for both optimised and non-optimised (single point run) runs.
So, i have two CHGCAR files.
Using vaspkit i did charge density difference subtracting from say, Optimised CHGCAR minus non-optimised CHGCAR, giving raise to another similar formatted CHGDIFF.vasp file.
Now, i wish to create a 2D plot to show the integrated values of charge along z-direction.
assuming the option '315' in vaspkit, i run the option, gave input of this CHGDIFF.vasp and asked two values in 'a' and 'b' directions. not clear what these values for, i gave '1 and 1'.
Then it gave three .grd format files. I could not open these files in vesta. when i try the VESTA is shutting down. These files cant be opened in Material studio also.
Can anyone help to understand How to do such integration either with vaspkit or otherwise 'numerically'.?

Now, using these vtst tools, can i get such integration of 2D grid values of CHGCAR? so that i can plot the 2D plot with color grading figure similar to 'slice' in Vesta?

[graeme]

It seems that we don't have a script for exactly this task. That said, it would be quite easy to modify one of our chg* scripts, which will allow you to read chgcar files, and then integrate over which ever dimensions that you want.