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["Bohdan Andriyevsky" <bandri@tu.koszalin.pl>]

Dear Konstantin and Andrew,
Thank you very much for your replies and advices.
After the calculation with 'abinis' I would like to calculate optical
conductivity of my crystal using the 'conducti'. But I do't know which set
of k-point for 'abinis' will be correct: one gamma-point, or the set
generated by 'kptopt=1' and 'ptrlen=35.0' for example.

I use PSP of the type 'xy-z.LDA.fhi'.
Thanks in advance for your reply.

Regards,
Bohdan

----- Original Message -----
From: "Konstantin Rushchanskii"
<Konstantin.Rushchanskii@physik.uni-regensburg.de>
To: <forum@abinit.org>
Sent: Thursday, March 31, 2005 12:20 PM
Subject: Re: [abinit-forum] How to achive the TE convergence?


> Dear Bohdan,
>
> I suppose, you have to pay attention to the following parameters:
>
> 1.) nstep can be too small to reach convergency for your system (50 is
> too small for so large systems).
> 2.) why do you use tsmear? If the compound is semiconducting, it is not
> neccessary.
> 3.) How many k-points do you use? You should use the nkpt variable
> instead of nqpt, or try to use ngkpt for setiing the MP mesh properly.
> 4.) Which kind of PSP's do you use? For atoms like H, O, C you need VERY
> large Ecut value. May be 80 Ha is not enough?
> 5.) Try to use iscf 5 (can be more stable and faster)
>
>
> You can also try to use a different kind of PSP.
> Hope this helps.
>
> Sincerely,
> Konstantin
>
>
> Bohdan Andriyevsky wrote:
>
> >Dear Abinit Users,
> >My crystal, (HN2CH2COOH)2HNO3, has 50 atoms in unit cell, and I can't
reach
> >convergence of total energy in the SCF calculations.
> >
> ># DGN - conductivity
> > enunit 2
> > prtvol 1
> ># - Parameters governing the convergence
> > ecut   80.
> > nband 168
> > occopt 1
> > tsmear 0.0002
> ># - Options for the choice of calculations
> > ixc   7
> > nstep 50
> ># SC run
> > iscf1   3
> > toldfe1 1.d-10
> > nqpt1   0
> > prtden1 1
> >
> >Please advise me the appropriate parameters of input file to reach the
> >convergence of total energy.
> >
> >Regards,
> >Bohdan Andriyevsky
> >
> >
> >
> >
>
>
> --
> K.Rushchanskii, Dr.
> Theoretische Physik, Universität Regensburg
> 93040 Regensburg Germany
> tel: +49 (0) 941-943-2466  fax: +49 (0) 941-943-4382
>

Dear Bohdan and Konstantin,

I agree with much of Konstantin's advice, but...

> 4.) Which kind of PSP's do you use? For atoms like H, O, C you need VERY
> large Ecut value. May be 80 Ha is not enough?

With OPIUM pseudopotentials (http://opium.sourceforge.net) you should
be able to use 50 Ry (25 Ha) cutoff with no problems for H, O, C, and
etc.

Regards,
Andrew M. Rappe