[Pw_forum] Constrained magnetic calculation

[paresh rout]

Respected Lorenzo sir,
                Thanks for your replay but my question was how to fix the
proper LAMBDA value for any constrained system as the energy is increasing
with increase in lambda value.Please suggest me something regarding lambda.



On Mon, Mar 3, 2014 at 5:54 PM, Lorenzo Paulatto <
lorenzo.paulatto at impmc.upmc.fr> wrote:

>  On 03/03/2014 12:39 PM, paresh rout wrote:
>
>  Dear all,
>           I am doing  spin polarized  calculations on a multiferroic
> compound . In some cases I am doing constrained magnetic calculations to
> get the Low-spin and High-spin state . For this I am using
>     constrained_magnetization='atomic'
>     starting_magnetization(1) = 5.0
>     starting_magnetization(2) = -3.0
>     starting_magnetization(3) = 0.0
>     starting_magnetization(4) = 0.0
>          lambda =0,5,10,20,25,........etc
>
>
>
>    +--------------------------------------------------------------------
>    Variable:       starting_magnetization(i), i=1,ntyp
>
>    Type:           REAL
>    Description:    starting spin polarization on atomic type 'i' in a spin
>                    polarized calculation.* Values range between -1 (all
> spins*
> *                   down for the valence electrons of atom type 'i') to 1*
> *                   (all spins up)*. Breaks the symmetry and provides a
> starting
>                    point for self-consistency. The default value is zero,
> BUT a
>                    value MUST be specified for AT LEAST one atomic type in
> spin
>                    polarized calculations, unless you constrain the
> magnetization
>                    (see "tot_magnetization" and
> "constrained_magnetization").
>                    Note that if you start from zero initial magnetization,
> you
>                    will invariably end up in a nonmagnetic (zero
> magnetization)
>                    state. If you want to start from an antiferromagnetic
> state,
>                    you may need to define two different atomic species
>                    corresponding to sublattices of the same atomic type.
>                    starting_magnetization is ignored if you are performing
> a
>                    non-scf calculation, if you are restarting from a
> previous
>                    run, or restarting from an interrupted run.
>                    If you fix the magnetization with "tot_magnetization",
>                    you should not specify starting_magnetization.
>    +--------------------------------------------------------------------
>
>
> kind regards
>
> --
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> phone:+33 (0)1 44275 084 / skype: paulatz
> www:  http://www-int.impmc.upmc.fr/~paulatto/
> mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 5
>
>
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