[ESPResSo-users] Porting to 3.1.0

[Michael Winokur]

Hi All,

So it has been a while but I've looking into running Gay-Berne
simulations on the 3.1.0 release as opposed to the 2.1.2 version I
have used in the past.  There are a lot of changes to be sure and so
it is a bit difficult to track down the underlying cause for
differences in the numerical values of a tcl test code.

One difference, which I believe may be a simple error, has to do with
the definition of GB_chi2 now located in gb.c.  The original
definition in 2.1.2  (in gb.h) was
  data->GB_chi2 =
(1-pow(data->GB_k2,(1/data->GB_mu)))/(pow(data->GB_k2,(1/data->GB_mu))+1);
but in 3.1.0 there is a sign change to specify
  data->GB_chi2 =
(pow(data->GB_k2,(1/data->GB_mu))-1)/(pow(data->GB_k2,(1/data->GB_mu))+1);

The values of energy and torques that I see in gb.h, as far as I can
tell, seem to give consistent numbers using the 2.1.2 expression.

Can someone kindly comment?  Am I missing something here?

Thanks,

Michael