[Wien] Volume has changed during running optimization of c/a with constant volume & b/a
shamik chakrabarti
shamik15041981 at gmail.com
Fri Jun 12 19:09:29 CEST 2020
Dear Prof. Peter,
I have sent the struct file after 4 successive
optimizations (a) volume, (b) c/a, (3) b/a, (4) force. That's why the
value is a bit different than the reported one in the mail. It is true that
different values of c/a do not change the value of constant volume. But my
question is the difference in conventional unit cell volume is coming
between the cases when we are obtaining unit cell volume from volume
optimization and in the next step while optimized c/a is calculated by
keeping the original volume constant.
Looking forward to listen from you.
with regards, .
On Fri, 12 Jun 2020 at 22:08, Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:
> Just to contribute to the complicated algebra:
>
> With your struct file the volume (:VOL in scf) is:
> :VOL : UNIT CELL VOLUME = 1072.33603
>
> This is different from what you wrote in your email ??? !!!!
> > coming as 1073.2425 bohr^3 which get doubles when we consider ....
>
> If I do
> x optimize
> option 3 (not 2, which is for tetragonal and hexagonal lattices!!!!)
> and 0 and 2% change:
>
> ca-test_coa____0.00.struct
>
> 11.264663 11.699300 16.273574 90.000000
> ca-test_coa____2.00.struct
>
> 11.190551 11.622329 16.489838 90.000000
> --------------------------------------------------
> cp ca-test_coa____2.00.struct ca-test.struct
> x lapw0
> grep :VOL *scf0
>
> The volume is still the same.
>
>
>
>
> Am 12.06.2020 um 17:32 schrieb shamik chakrabarti:
> > Another thing is that from volume optimization the unit cell volume is
> > coming as 1073.2425 bohr^3 which get doubles when we consider the volume
> > of a conventional cell to become 2146.485 bohr^3 while the printed
> > volume of a conventional unit cell after c/a optimization is coming as
> > 2058.7690 bohr^3 ; Why is this discrepancy? Is it that the conventional
> > cell volume about 1.9183 times the unit cell volume & not as I have
> > assumed. I am sending the fully optimized struct (according to my
> > calculation) file for your consideration.
> >
> > with regards,
> >
> > On Fri, 12 Jun 2020 at 20:46, shamik chakrabarti
> > <shamik15041981 at gmail.com <mailto:shamik15041981 at gmail.com>> wrote:
> >
> > Dear Tomas,
> > Can you please elaborate how to know a', b' and c'
> > (the final lattice parameters) from a unit cell volume optimization
> > with a:b:c = constant (where a, b, c are initial lattice parameters)
> ?
> >
> > with regards,
> >
> > On Fri, 12 Jun 2020 at 17:15, Tomas Kana <kana at seznam.cz
> > <mailto:kana at seznam.cz>> wrote:
> >
> > Dear Shamik,
> > Ok, I undestand your point.
> > But anyway, I think, that the problem comes
> > from your equation.
> > If you want to relax c/a with constant volume and
> > constant b/a then I would prefer these eqations:
> > original c/a = cAoriginal
> > b/a = bAconstant
> > new c/a = cAnew
> >
> > original volume a*b*c
> > new volume (the same as original)
> > aNew * bNew * cNew =
> > aNew * (aNew * bAConstant) * (aNew * cAnew) =
> > aNew^3 * bAConsant*cAnew = original volume
> > You choose your desired cAnew and know0 bAconstant
> > and the original volume.
> > In this way, you obtain the aNew and it is easy to
> > obtain bNew and cNew then. But I still do not understand the
> > parameter x in your eqation.
> > Maybe this could be the source of your error?
> > Hope this helps
> > Tomas
> >
> > Dear Tomas,
> >
> > I am sorry to say that you have misunderstood
> > my equation. I have used abcx^3 = a'b'c' where a', b' and c' are
> > the new lattice parameters & not the old a,b,c !!! :)
> >
> >
> > with regards,
> >
> >
> > On Fri, 12 Jun 2020 at 16:31, Tomas Kana <kana at seznam.cz
> > <mailto:kana at seznam.cz>> wrote:
> >
> > Dear Shamik,
> >
> >
> >
> > If you want to keep a constant volume and
> >
> > you use the equation
> >
> > abcx^3 = 332.934 = abc then only one solution is possible:
> >
> > x = 1. ax = a, bx = b cx = c.
> >
> > Your equation does not make sense to me....
> >
> > With best regards
> >
> > Tomas Kana
> >
> >
> >
> >
> >
> > where a, b, c are the initial lattice parameters. From that
> > equation I have found the value of x & then finally multiply x
> > with each lattice parameters to get new lattice parameters as
> > a* = ax, b*=bx & c*=cx & then put
> >
> >
> >
> >
> >
> > ---------- Původní e-mail ----------
> >
> >
> >
> > Od: shamik chakrabarti <shamik15041981 at gmail.com
> > <mailto:shamik15041981 at gmail.com>>
> >
> >
> >
> > Komu: A Mailing list for WIEN2k users
> > <wien at zeus.theochem.tuwien.ac.at
> > <mailto:wien at zeus.theochem.tuwien.ac.at>>
> >
> >
> >
> > Datum: 12. 6. 2020 10:05:37
> >
> >
> >
> > Předmět: Re: [Wien] Volume has changed during running
> > optimization of c/a
> >
> > with constant volume & b/a
> >
> >
> >
> > No, I have created a new directory for c/a optimization. I have
> > done the followings,
> >
> >
> >
> > abcx^3 = 332.934 where a, b, c are the initial lattice
> > parameters. From that equation I have found the value of x &
> > then finally multiply x with each lattice parameters to get new
> > lattice parameters as a* = ax, b*=bx & c*=cx & then put
> >
> >
> >
> > a*,
> >
> >
> >
> > b* & c* as new inputs for c/a optimization with constant volume
> > in a new directory.
> >
> >
> >
> >
> >
> > with regards,
> >
> >
> >
> >
> >
> > On Fri, 12 Jun 2020 at 13:23, Peter Blaha
> > <pblaha at theochem.tuwien.ac.at
> > <mailto:pblaha at theochem.tuwien.ac.at>> wrote:
> >
> >
> >
> > How did you do:
> >
> >
> >
> >
> >
> >
> >
> > "putting the lattice parameters as input for c/a optimization"
> ???
> >
> >
> >
> >
> >
> >
> >
> > If you continue in the previous directory, do you realize that
> > there is
> >
> >
> >
> > a case_initial.struct which, if present, is taken a "base
> > struct file".
> >
> >
> >
> >
> >
> >
> >
> > Am 12.06.2020 um 04:12 schrieb shamik chakrabarti:
> >
> >
> >
> > > Dear wien2k users,
> >
> >
> >
> > >
> >
> >
> >
> > > I am running wien2k 19.1. I have started c/a
> > optimization
> >
> >
> >
> > > with constant volume and b/a for an ABO4 compound. From volume
> >
> >
> >
> > > optimization with a:b:c=constant I have obtained an unit cell
> > volume of
> >
> >
> >
> > > 332.934 Ang^3. While after calculation of lattice parameters
> > and putting
> >
> >
> >
> > > the lattice parameters as input for c/a optimization with
> > *constant
> >
> >
> >
> > > volume* & b/a, the printed unit cell volume is coming
> > as 312.8004 Ang^3.
> >
> >
> >
> > >
> >
> >
> >
> > > Where I am doing wrong?
> >
> >
> >
> > >
> >
> >
> >
> > > Thanks in advance.
> >
> >
> >
> > >
> >
> >
> >
> > > with regards,
> >
> >
> >
> > > --
> >
> >
> >
> > > Dr. Shamik Chakrabarti
> >
> >
> >
> > > Research Fellow
> >
> >
> >
> > > Department of Physics
> >
> >
> >
> > > Indian Institute of Technology Patna
> >
> >
> >
> > > Bihta-801103
> >
> >
> >
> > > Patna
> >
> >
> >
> > > Bihar, India
> >
> >
> >
> > >
> >
> >
> >
> > > _______________________________________________
> >
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> >
> >
> > >
> >
> >
> >
> >
> >
> >
> >
> > --
> >
> >
> >
> > Peter Blaha
> >
> >
> >
> > Inst.Materials Chemistry
> >
> >
> >
> > TU Vienna
> >
> >
> >
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> >
> >
> >
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> >
> >
> >
> >
> >
> >
> > --
> >
> > Dr. Shamik Chakrabarti
> >
> > Research Fellow
> >
> > Department of Physics
> >
> > Indian Institute of Technology Patna
> >
> > Bihta-801103
> >
> > Patna
> >
> > Bihar, India
> >
> >
> >
> >
> >
> >
> >
> >
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> >
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> >
> >
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> >
> >
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> >
> > --
> > Dr. Shamik Chakrabarti
> > Research Fellow
> > Department of Physics
> > Indian Institute of Technology Patna
> > Bihta-801103
> > Patna
> > Bihar, India
> >
> >
> >
> >
> >
> >
> >
> >
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> > --
> > Dr. Shamik Chakrabarti
> > Research Fellow
> > Department of Physics
> > Indian Institute of Technology Patna
> > Bihta-801103
> > Patna
> > Bihar, India
> >
> >
> >
> > --
> > Dr. Shamik Chakrabarti
> > Research Fellow
> > Department of Physics
> > Indian Institute of Technology Patna
> > Bihta-801103
> > Patna
> > Bihar, India
> >
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>
> --
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
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--
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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