Thanks a lot!!!!!

both options worked well, but I think I prefer the first one!
I got bigger MM Forces than QM forces in one snapshot...
I have to check it out!
THANKS a lot!!!!
BR,
noelia

# set radius [min [expr 0.1 * [veclength $vec]] $radius]

I am running it in linux and as you see there is nothing unusual.
I got huge arrows! (see the attach)

I am using that version:

Info) VMD for LINUXAMD64, version 1.9.1 (February 1, 2012)

yes!
After loading the last force it says

can't set "vmd_frame(2)": invalid command name "min"

Hi Lee-Ping, thanks for the answer. what you said, it is what I did. That is why I think it might be my vmd version, I don't know! Now I came back to the old file you sent me, (you sent once a noelia1.tar.gz file) just in case, but even in this case I couldn't see the arrows. I attached those three ...

Hi Lee-Ping, So far so good, I am getting some results, but still not what I expected, I tried to plot the forces as you suggested, but without succeed. I used your script drawforces.vmd and copy the QMforce.xyz and MMforce.xyz from the temp directory. I used both the all.gro and the coord.xyz files...

Dear Lee-Ping, I am still having some problems in getting good numbers for the parameters, so I have decided to start with a simpler system: Ti4+ as a residue with one atom, and, for the moment, a first shell of 5 or 6 TIP3P water molecules. I decided for this sytem, because I already have 200 confi...

Dear Lee-Ping, sorry for the delay in answering, but I wanted first to carry on the calculations you have suggested. First of all, let me thank you for your help. It is very appreciated and your prompt replies let me progress faster than I have thought. I am also glad that you could use my "errors" ...

I add the all.gro file here

Dear Lee-Ping, thanks a lot for your help !! I have solved part of the problems, but some of them are still open. In particular, this particular error had to do with the fact that by using nwchem and qchem, the molecule was re-oriented to a standard orientation and the all.gro and qdata.txt were not...