Dear user,
Many thanks for your reply. I am not able to understand, where I have choosen
cutoff for all basis is 0. Kindly specificly gude me so I can make necessary
changes at appropriate place to get proper output.
Regards,
Nidhi
N H <[EMAIL PROTECTED]> wrote: Dear Nidhi ..
Excuse-me, but have u noticed that you cut off for all basis is ZERO?!
It means that all of your electrons are confined to the nucleous...
all of then, n this way u have no bonds formation and a huge
electronic repulsion I would say ... U need to especiffy your cut off
radius resoanably!
Cheers..
NH
On Wed, Apr 9, 2008 at 1:13 PM, Nidhi Sharma wrote:
> Hi,
>
> I have made the changes according to u and defined the pseudo of Sm as
> pg Samarium
> tm2 3.0 # PS flavor, logder R
> n=Sm c=ca # Symbol, XC flavor,{ |r|s}
>
> 0.0 0.0 0.0 0.0 0.0 0.0
> 11 4 # norbs_core, norbs_valence
> 6 0 2.00 0.00 # 6s2
> 6 1 0.00 0.00 # 6p0
> 5 2 0.00 0.00 # 5d0
> 4 3 6.00 0.00 # 4f6
> 3.11 4.10 3.11 3.11 0.00 0.00
> and Te as
> pg Tellurum
> tm2 3.0
> n=Te c=ca
> 0.0 0.0 0.0 0.0 0.0 0.0
> 9 3
>
> 5 0 2.00 0.00
> 5 1 4.00 0.00
> 5 2 0.00 0.00
> 2.57 2.63 2.57
> but when I define the PAO basis like
>
> %block PAO.Basis
> Sm 2 # Label, l-shells
> n=6 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
> 0.000 0.000
> 1.000 1.000
> n=6 1 2
>
> 0.000 0.000
> 1.000 1.000
> n=5 2 2
>
> 0.000 0.000
> 1.000 1.000
> n=4 3 2
>
> 0.000 0.000
> 1.000 1.000
> Te 2 # Species label, number of l-shells
> n=5 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
> 0.000 0.000
> 1.000 1.000
> n=5 1 2 # n, l, Nzeta
> 0.000 0.000
> 1.000 1.000
> n=5 2 2 # n, l, Nzeta
> 0.000 0.000
> 1.000 1.000
> %endblock PAO.Basis
>
>
> Then I got this kind of error on the command line
>
> reinit:
> -----------------------------------------------------------------------
> reinit: System Name: SmTe
> reinit:
> -----------------------------------------------------------------------
> reinit: System Label: SmTe
> reinit:
> -----------------------------------------------------------------------
>
>
>
> initatom: Reading input for the pseudopotentials and atomic orbitals
> ----------
> Species number: 1 Label: Sm Atomic number: 62
> Species number: 2 Label: Te Atomic number: 52
> Ground state valence configuration: 6s02 4f06
> Reading pseudopotential information in formatted form from Sm.psf
> Ground state valence configuration: 5s02 5p04
> Reading pseudopotential information in formatted form from Te.psf
> WRONG species symbol in PAO.Basis: n
>
> Stopping Program from Node: 0
> Again I mabe the changes in PAO basis as
> %block PAO.Basis
> Sm 2 # Label, l-shells
> n=6 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
> 0.000 0.000
> 1.000 1.000
> n=4 3 2
>
> 0.000 0.000
> 1.000 1.000
> Te 2 # Species label, number of l-shells
> n=5 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
> 0.000 0.000
> 1.000 1.000
> n=5 1 2 # n, l, Nzeta
> 0.000 0.000
> 1.000 1.000
> %endblock PAO.Basis
>
> then the program run successfully but lattice parameter and band gap is far
> from our expt values. May you please check my .fdf file and guide me where
> should make the appropriate changes. I m enclosing .fdf file, .out file,
> psf file and band structure (looks like metallic) that we obtained.
>
> Many thanks in advance.
>
>
> [EMAIL PROTECTED] wrote:
>
> You mix up several things; I doubt it will help to resolve your problems
> but let us address them one by one.
>
> Sm valence configuration. 4f states are quite localized and
> probably (in reality, not in DFT the calculation) are not any near
> to the band gap. If you include them in valence states and in the basis,
> your trouble will be not performing the calculation as such,
> but their wrong calculated positioning (at the Fermi level).
> If you attribute them to core... I don't know there is an easy way
> to do this, because the 4f shell is not fully occupied.
> Search for previous calculations (any method, with DFT and beyond)
> on RE chalcogenides, and on any RE calculations using pseudopotentials.
>
> > Dear users, as we know the valence configuration of Sm is 4f6,6s2. In
> > order to combine it with chalcogenides it is necessary to make the net
> > ionic charge of Sm to 2, means we have to consider the 4f6 in the core.
>
> Why necessary? The "net ionic charge", whatever its definition, will come
> out of your calculation somehow. To begin with, you start from neutral
> atoms, and they remain neutral, whether you attribute 4f to the core
> or to the valence states...
>
> > When we define the PAO basis set as
> >
> > %block PAO.Basis
> > Sm 2 # Label, l-shells
> > n=6 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
> > 0.000 0.000
> > 1.000 1.000
>
> Don't forget to include 5d in the basis; they are IMPORTANT.
>
> > Te 2 # Species label, number of l-shells
> > n=5 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
> > 0.000 0.000
> > 1.000 1.000
> > n=5 1 2 # n, l, Nzeta
> > 0.000 0.000
> > 1.000 1.000
> > %endblock PAO.Basis
>
> Your Te might be OK (or not); at least no obvious faults.
>
> >
> > it will display the following message
> > reinit:
> > reinit: System Label: SmTe
> > -----------------------------------------------------------------------
> > initatom: Reading input for the pseudopotentials and atomic orbitals
> > ----------
> > Species number: 1 Label: Sm Atomic number: 62
> > Species number: 2 Label: Te Atomic number: 52
> > Ground state valence configuration: 6s02 4f06
> > Reading pseudopotential information in formatted form from Sm.psf
> > Ground state valence configuration: 5s02 5p04
> > Reading pseudopotential information in formatted form from Te.psf
> > Bad format of (n), l, nzeta line in PAO.Basis
> > Stopping Program from Node: 0
>
> This is probably because you promised 2 functions in the basis block for Sm
> but passed only one (6s). Make it consistent.
>
> > If I include the 4f6 in basis set it will make the net charge 8 and behave
> > as a semi core.
>
> This "net charge" is not exactly your worry. It simply gives you the number
> of electrons provided by the atom in question to the valence band,
> in does not yet make from Sm a 8+ ion. Similarly, you can choose
> the Te configuration either as 5s2 5p4 5d0 (6 valence electrons)
> or 5s2 5p4 4d10 (16 valence electrons), it is still the same atom.
> Only, you'll have different number of bands. I repeate, the decision
> to put Sm 4f in the core or in the valence is only your - difficult,
> but free - choice.
>
> Now we come to Te.
>
> > If I use a already generated pseudo file of Te which include 5s2, 5p4, 4d0
> > and 4f0 But how can 4d0 is possible although it contains 10 electrons.
>
> This is a misprint in the head line of the Te pseudo. It was generated
> with 4d10 in the core and 5d as valence states. (Ask Eduardo Anglada).
>
> > When I use this file then we get results but band gap in B1 phase
> > is ~10eV which is quite far from the expt 0.67eV.
>
> This can be due to anything. (In fact an absence of Sm5d in the basis
> is a good candidate). Try to look not only at the band gap value
> (which will be wrong anyway) but at the density of states,
> positioning of different groups of valence bands. The band structure
> of RE chalcogenides is well known.
>
> > Please help me how can i resolve the problem of valence charge .
>
> I don't see there is a problem, in fact. The (technical) problem is -
> if you want to remove 4f from the valence - how to declare them as core,
> even as this shell is not fully occupied. But by default, you can
> go ahead with 4f as valence states (in BOTH basis and pseudopotential).
> Then you'll see that the positioning of the 4f is wrong, and start
> to think how bad this is for the problem your have to solve,
> and what to do about it. This is not a SIESTA problem, but one
> which appeared before in other DFT calculations.
>
> Good luck,
>
> Andrei Postnikov
>
>
>
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