QM/MM with point charge equal to zero problem

I am recently using Q-CHEM to carried out QM/MM calculations, and I have some point charges with zero charge. Just like this:
-8.51710727 -3.96383986 -1.96067631 0.00000000
-8.48687774 -3.91199616 -1.96727712 0.00000000
-8.69900583 -4.09370930 -2.04906479 0.00000000
-8.47654720 -4.83214256 -2.36147128 0.00000000

After the calculation, I found that the forces on these point charges are not zero as I checked the efield.dat file. The results are:
0.00009224266 0.00000713111 -0.00019090695
0.00009510766 0.00000809305 -0.00019357297
0.00008696419 0.00000482941 -0.00017600281
0.00008841079 0.00001597472 -0.00015747707

So I don’t know if there is something wrong with my input file or there is something I need to take care of.
Any suggestions are appreciated.
Thanks in advance.

The efield.dat file contains electric field vectors for each point charge. To obtain the force, electric field is multiplied by the charge. Zero charge will yield zero force.

1 Like

Thank you very much.
This has confused me a lot.