[gmx-users] non-symmetric matrix and too large first values

[medeawan at sohu.com]

dear all,
I want to calculate the Normal Mode of some proteins and DNA in vacuum. When I use the command g_nmeig_d after EM(Max force < 1e-7), for some structures everything is ok (the first six eigenvalue <1e-4), but for some structures I get the following message:
"possible non-symmetric matrix:
x[311][103]=2.017657e-04,x[103][311]=2.017515e-04
.........

One of the first eigenvalues has a non-zero value.
This could mean that the reference structure was not
properly energy minimised"
and for others only the "possible non-symmetric matrix" message.
Is there something wrong?
Thanks for any help.
                                     
                                        

                                             Sincerely yours
                                                    Medeawan