Robert,

It is absolutely possible to do this, the total energy is printed a few
times when the run ends.
To calculate single point energy, use:

MD.TypeOfRun          cg
MD.NumCGsteps         0

So that atoms are frozen in place, then once the run is finished either look
for a "siesta: total Energy" line in the output file, or you can use grep to
look for the specific line in the file. Try:

>> fgrep "siesta: FreeEng"
if you want the free energy or

>> fgrep "siesta: Etot"
for the total energy (in many instances, they will be the same). The grep
command used this way will return two values, the first is the (unconverged)
total energy from the beginning of the run, and the second is the converged
energy at the end of the cg/scf loop. Towards the end of the output file,
you can also find lines like these:

siesta: Final energy (eV):
siesta:  Band Struct. =  -28113.082516
siesta:       Kinetic =   62511.903467
siesta:       Hartree = 1851209.928718
siesta:    Ext. field =       0.000000
siesta:   Exch.-corr. =  -19076.142766
siesta:  Ion-electron =-3768244.293672
siesta:       Ion-ion = 1753136.700291
siesta:       Ekinion =       0.000000
siesta:         Total = -120461.903961

Where the energy is partitioned into all of its components. You have to
carry the calculation through to completion, either by satisfying some
atomic force convergence condition or a maximum of conjugate gradient steps
to get this information, so you won't see it if you are interrupting the
calculation somehow.

Best of luck,

Abraham Hmiel
Katherine Belz Groves Fellow in Nanoscience
Xue Group, College of Nanoscale Science and Engineering at SUNY Albany

On Tue, Oct 4, 2011 at 7:53 AM, <[email protected]> wrote:

> Hello SiestaUsers,
>
> I'm new member of SiestaUsers family. I have one small question,
> is it possible to calculate only single point (electronic) energy with
> siesta ... . In my output I can see also gradients, but I would like to
> calculate only energy.
>
> Thanks in advance.
>
> Best Regards
>
> Robert Sedlak
>
>
>
>
>

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