The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Waigen Zhang,

On 21 Jul 2007, at 17:36, waigen zhang wrote:

> Dear all,
> What does the first derivative mean in DS1_DDB file? If they are  
> total energy's first derivative wrt coordinates,then what's the  
> difference between DS1_DDB and the force in .out file.

Derivates are with respect to reduced coordinates, forces are in  
cartesian coordinates ...

> Should we take the first derivative into account when doing  
> optimization?

I am not suer to understand your question.
Forces are of course taken into account when you use ionmov in ABINIT

> What's the second column(zeros) and last 6 lines in DS1_DDB?

The second columns are irrelevant. Last 6 lines might be used.
SImply derivatives with respect to other perturbation. Read the respfn
user guide ...

Best,
Xavier