Multiwfn forum

Thank you, Sir, for your prompt reply. So, is there a way in Multiwfn to get RMSE and RRMSE of a certain atom using a set of charges specified by the user but the user has control over the grid points in ESP like spacing and extension distance? Actually I am trying to implement a procedure as given in the paper--- Kramer, C., Spinn, A., and Liedl, K. R. “Charge anisotropy: Where atomic multipoles matter most”. Journal of Chemical Theory and Computation, 10(10), pp. 4488–4496 (2014)

Sir, apologies for not making it understandable, by "octamer" I mean "two monomers "of the polymer used for calculation and by "long molecule" I mean  "25 monomers" of the polymer used. I know RESP fitting is better than CM5, but for comparison of charges I do have to consider all the charges.
I took an octamer for calculation, since it is the best representation of the polymer by some experimental results. Now, the problem that arises is getting a neutral condition, So, I made some small adjustments to the charges obtained by DFT in the fourth decimal of the charges of atoms to make it a neutral for MD purpose.
Is there any better way than this to obtain CM5 charges for the polymer (long chain)?

Okay Sir, Thank you for helping me out. I will look at the distribution of points in VMD.

Thanks Sir for your prompt reply.
Here are my details, I want to calculate the RMSE of the .chg file with Quantum ESP using MK fitting mode
There is an option of selecting the MK layers in the menu, I want to select all the points lying in between 1.66 of the vdw radius to 2.20 of the vdw radius of a particular atom. I am giving the layers option as 1.66,1.67, 1.68...till 2.20, so 55 layers. Then it yields a statement that 11020 points are being used. I am attaching some pics of the screen where commands are mentioned.
So, I would like to know from you if I am doing it the correct way?

If this method is wrong is there any way to do this of getting RMSE of a specific atom within a particular range of vdw radius specified by user, using any fitting method in Multiwfn?

Thank you Sir for your answer. I will surely do the protocol as mentioned.

Is there any way out by which we can calculate the electrostatic potential map generated by the atomic charges which could assist to find out the solubility parameter?

Sir,
When the RMSE appears on the screen, what is it's unit?Is it in a.u. as mentioned in page 277

Sorry Sir for the incomplete msg
I wanted to use my own specified grid setting and then calculate the RMSE of the molecule
For this I used the C2H2.wfn file. These are the steps I followed
1. Went to main function 5 (Output and plot specific property within a spatial region)
2. Then went available real space function option 12( Total electrostatic potential
3. Seting up grid by option 4 (grid spacing)
4. Inputting the grid spacing in bohr unit e.g 0.56 in all directions
5. Exporting the data via option 2 (a cube file generated)
6. I did some additional settings in order to change the extension distance of the molecule went to settings.ini and changed the Aug3D
7. Booted Multiwfn again
8. I had chosen the cube file generated before (step 5 I mentioned)( I wanted to have the grid setting as I had set so I uploaded the cube file)
9. Went to main function 7(  Population analysis)
10. Then in Population analysis I opted for 13 ( MK mode)
11. Then I gave -3 as I wanted to compare the atomic charges from CM5 ( already produced stored in .chg file)
12. Gave the path to the file. Opted for option 3 to set the layers since I want the grid points lying within a particular range from 1.66 to 2.2 of vdw radius of a specified atom. I gave layer one 1.66 and layer two 2.2 so that only those grid points are considered lying in the range while calculating esp and others are not considered.
13. I then opted for option 4 choosing atoms. I gave 1 as input if I want to check the esp of 1st atom
14. Then selected 1 as option for starting calculation.
15. It gave me output
Sum of charges -0.000036
RMSE 2.29.  RRMSE 1.000963
So by this can I take that the error in producing ESP of the carbon atom when measured with quantum esp is 2.29.
I am new to DFT and learning it so I am having problems

Thank you Sir for being so prompt in replying to queries. I do need an option where I can calculate the RMSE error of a specific atom in a given molecule, if I upload the chg file. It will be so useful if such an option will be available in Multiwfn

Hello Sir,

Apologies to disturb you once again, is there any way out in Multiwfn to calculate the RMSE error around a specific atom?