[Wien] About mini_lapw

[Stefaan Cottenier]

You seem to confuse the convergence of forces within one scf cycle (with
the convergence criterium given by -fc), and the optimization of
internal positions until forces on these positions are low (done by
min_lapw, with convergence criterium TOL in case.inM).

In your case, your initial structure had low forces already. The scf
cycles stops when there are almost no variations of the forces left
(11.13 to 11.17, much less than the requested -fc 1), and therefore in
the last iteration Pulay corrections are added to get the final force
(1.84). Now min_lapw checks whether each of the force components in the
absolute axis system meets the TOL criterium (by default 2). This is the
case: 1.84 < 2. Therefore, no structure optimization is started.

If you would reduce TOL to 1, you would see something happening. But
changes in positions will be very small in this case.

Stefaan


Hui Wang wrote:
> Dear wien2k master:
>     I wanna use mini_lapw to optimize the internal position of atom in 
> unit cell, my questions are as follows:
>     (1)run regular scf first , and rerun mini_lapw -p -I -j "runsp_lapw 
> -I -fc 1.0 -cc 0.001 -ec 0.0001 -i 200", but the :FGL*** and :FOR***
> ==================
> :FGL002:   2.ATOM               -11.083898500   -11.083898500     
> 0.000000000 partial forces
> :FGL002:   2.ATOM               -11.066220831   -11.066220831     
> 0.000000000 partial forces
> :FGL002:   2.ATOM               -11.139406381   -11.139406381     
> 0.000000000 partial forces
> :FGL002:   2.ATOM               -11.186428981   -11.186428981     
> 0.000000000 partial forces
> :FGL002:   2.ATOM               -11.178297253   -11.178297253     
> 0.000000000 partial forces
> :FGL002:   2.ATOM                 1.842720223     1.842720223     
> 0.000000000 total forces
> -------------------------
> :FOR002:   2.ATOM         16.284          0.000          0.000        
> -16.284 partial forces
> :FOR002:   2.ATOM         16.131          0.000          0.000        
> -16.131 partial forces
> :FOR002:   2.ATOM         15.675          0.000          0.000        
> -15.675 partial forces
> :FOR002:   2.ATOM         15.650          0.000          0.000        
> -15.650 partial forces
> :FOR002:   2.ATOM         15.753          0.000          0.000        
> -15.753 partial forces
> :FOR002:   2.ATOM         15.820          0.000          0.000        
> -15.820 partial forces
> :FOR002:   2.ATOM         15.809          0.000          0.000        
> -15.809 partial forces
> :FOR002:   2.ATOM          2.606          0.000          0.000          
> 2.606 total forces
> =============================
> it seems that just one step the force meet the criterium, but i set -fc 
> 1.0 , how can it stop since the force still bigger than 1.
>       (2)After the mini process, and assume it meet the criterium, where 
> can I get the new struct ? ( I check the .struct, it is not updated)
>       Thanks:)
>  
> Hui
> 
> 
> 
> 
> 
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-- 
Stefaan Cottenier
Center for Molecular Modeling (CMM)
Ghent University
Technologiepark 903 (2nd floor)
BE-9052 Zwijnaarde
Belgium

http://molmod.Ugent.be
email: Stefaan . Cottenier /at/ UGent . be