The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <xavier.gonze@uclouvain.be>]

Dear Igor Lukacevic,

On 17 Feb 2009, at 08:10, ilukacevic@fizika.unios.hr wrote:

> Dear X. Gonze,
>
> Yes (I've included an .in file in my first post, but forgot to  
> reattach it in
> the following posts - sorry for that), I'm using ecutsm, with the  
> value of 0.1
> Ha (the same one in structural relaxation and rf calc.). I haven't  
> tried to
> optimize its value...yet. Do You think its too low?

The recommended value is 0.5 Ha. 0.1 Ha seems low but perhaps  
sufficient. At least,
you should give a try with the recommended value (and use it  
consistently for geometry optimization
and rf calculations).
> But I'm not using the same value of ecut in structural relaxation  
> calc. (52 Ha)
> and rf calc. (60 Ha).

Always better to be consistent. At least you should have done the  
generation of GS wavefunctions
for subsequent rf calculation with the 60 Ha value...

X. Gonze

> Could this be the cause of the slow convergence?
> I know that because of that I receive an difference in stress tensor  
> components
> between struct. relax. and rf calc.:
>
>
>
>
> > > > > > > > > > Etotal= -7.21370977356432E+01
> Cartesian components of stress tensor (hartree/bohr^3)
>  sigma(1 1)= -1.35956626E-03  sigma(3 2)=  0.00000000E+00
>  sigma(2 2)= -1.35956626E-03  sigma(3 1)=  0.00000000E+00
>  sigma(3 3)= -1.35956885E-03  sigma(2 1)=  0.00000000E+00
>                                                                         
>                                                 <-- struct. relax. calc.
> -Cartesian components of stress tensor (GPa)[Pressure=  4.0000E+01 GPa]
> - sigma(1 1)= -3.99998150E+01  sigma(3 2)=  0.00000000E+00
> - sigma(2 2)= -3.99998150E+01  sigma(3 1)=  0.00000000E+00
> - sigma(3 3)= -3.99998915E+01  sigma(2 1)=  0.00000000E+00
>
>
>
>
> > > > > > > > > > Etotal= -7.21382669702764E+01
> Cartesian components of stress tensor (hartree/bohr^3)
>  sigma(1 1)= -1.35946560E-03  sigma(3 2)=  0.00000000E+00
>  sigma(2 2)= -1.35946560E-03  sigma(3 1)=  0.00000000E+00
>  sigma(3 3)= -1.35776261E-03  sigma(2 1)=  0.00000000E+00
>                                                                         
>                                                  <-- rf calc.
> -Cartesian components of stress tensor (GPa)[Pressure=  3.9980E+01 GPa]
> - sigma(1 1)= -3.99968535E+01  sigma(3 2)=  0.00000000E+00
> - sigma(2 2)= -3.99968535E+01  sigma(3 1)=  0.00000000E+00
> - sigma(3 3)= -3.99467501E+01  sigma(2 1)=  0.00000000E+00
>
>
> Could this be also the cause?
>
>
> Thank You in advance!
>
> Igor Lukacevic