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[ESPResSo] New thermostat and empirical finding

From: Christopher Jesudason
Subject: [ESPResSo] New thermostat and empirical finding
Date: Wed, 15 Aug 2007 12:07:47 -0700 (PDT)

Dear Friends,
Ever since using the  latest version of Espresso, two
points were noted:
1) The setmd temperature xxx does not work as it did
2) THe temperature in the set thermostat command
produces an actual temperature DOUBLE (factor of two)
of what is set in the program. For instance, 
set gamma     0.1
set temp      3.00000
thermostat langevin $temp $gamma 
produces a temperature of  T= 6.07594775952 or so
whenever the temperture is probed. I varied the
temperature setting and in each case a factor of two
was observed. 
Kindly verify this.
Best Wishes, Happy 15 August,
--- Olaf Lenz <address@hidden> wrote:

> Hash: RIPEMD160
> Hi!
> Christopher Jesudason wrote:
> > coulombic interactions as { coulomb -5157.21849993
> > 850.397598161 -6007.61609809 }, where the first
> entry
> > is the sum of the last two; I presume that the
> first
> > entry is the total coulombic energy; what does the
> > other   two energies represent ? 
> This is a good question, I notice that it is not
> documented. I've just
> added a note to our todo-list.
> The energy components are indeed the real and
> reciprocal space
> components of the energies as obtained from the P3M
> algorithm, which is
> closely related to the Ewald summation.
> When you use P3M, please make sure that you
> understand the meaning of
> the different parameters and how to tune them, as
> you can severely mess
> up things if you don't! Refer to the following
> article if you need a
> reference (the original paper of Hockney and
> Eastwood is not what you
> want to read):
> Deserno, M. & Holm, C. How to mesh up Ewald sums. I.
> A theoretical and
> numerical comparison of various particle mesh
> routines. J. Chem. Phys.,
> 1998, 109, 7678
> Best regards
>       Olaf
> Version: GnuPG v1.4.2 (GNU/Linux)
> Comment: Using GnuPG with SUSE -
> T6Itt6OmtTG9N2wnKIxgg6s=

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