[CPMD-list] Units in geometry files

[Michael Hawlitzky]

Dear all,

I have a question of units concerning the GEOMETRY file:
In the manual it is stated that the units of that file are positions in 
a.u. (col. 1-3) and velocities in bohr/a.t.u. (col. 4-6). This is of 
course the case for MD runs.
But is this still the case when one performs just a wavefunction 
optimization in order to get the interatomic forces (this would then 
mean 1-step-velocities)?
Here the numerical values of the final results in the CPMD output file 
in the columns titled GRADIENTS (-FORCES) are the same (except for 
rounding) as in columns 4-6 of the GEOMETRY file.

And would the formula to translate it into correct force units 
([F]=Ha/bohr) be:
v/<timestep>*<mass>    , where v would denote a value from column 4-6 of 
the GEOMETRY file after a wavefunction optimization?

Another question: What are the exact units in the GEOMETRY.XYZ file? In 
the manual there is just written "in $\AA$", but what does this mean for 
the velocities? $eV/\AA$ or maybe $\AA/1a.t.u.$ ?

Thanks for your attention,
Michael Hawlitzky

-- 
Dipl.-Math. Michael Hawlitzky
Institut für Physik, Universität Mainz
Staudingerweg 9, Raum 01-517
55099 Mainz
Tel.: (+49)6131-3925158
Fax:  (+49)6131-3925441