[Wien] LDA-GGA and van der Waals
Osama Yassin
oyassin63 at gmail.com
Mon Mar 9 17:09:08 CET 2015
Dear Prof Blaha,
With reference to the paper
*Calculation of the lattice constant of solids with semilocal
functionalsPhilipp Haas, Fabien Tran, and Peter Blaha*
*PHYSICAL REVIEW B79, 085104 2009*
For layred metal dichalcogenides (e. g. WS2), does it sound correct if the
difference between the lattice constants obtained by LDA and that obtained
GGA is equivalent to the lattice contraction due to van der Waals forces?
*Osama *
*Department of Physics, Faculty of Science*
*Taibah University, A-Madinah Al-Munawarh, K. Saudi Arabia*
*A man would do nothing if he waited until he could do it so well that no
one could find fault.*
On Sat, Mar 7, 2015 at 10:24 AM, Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:
> There is a misunderstanding: No, don't take a "mean" energy.
>
> Check also the corresponding charge. When it is large, it is a major
> component and needs an energy parameter close to this energy.
>
> In case.scf2 you can find under the line :EPH and :EPL
>>> the "mean" energy of the P-s states. If they are not close to -0.73
>>> (thats where you expand P-s), change the corresponding input value.
>>>
>>
>> For P-s, :EPL and :EPH are -1.34 and -0.43, mean of -0.89, fairly close to
>> -0.73?
>>
>
> Together with the large P-s charge in :EPL it tells you, that you should
> lower the P-s parameter in case.in1 to -1.34
> Whether one sets in addition a second l=0 Eparameter in case.in1 depends on
> the E-separation between these EPL and EPH values, corresponding charges
> and the sphere radii (the larger the spheres: more probably yes).
> Here you have 0.9 Ry difference, but presumably the P-s charge in the
> upper E-window is
> very small and you have a very small spheres. Setting the two
> energies to those values might lead to ghostbands and at least at the
> beginning you
> moved one E-parameter up to +6 Ry. As I said previously, you may test it
> at the end
> and set the second Al-s line to 0.30 (no search), so that the actual
> E-parameter will be EF+0.2
>
> Other than P-s they are not close. Al-s has -7.24, -0.34, mean of -3.79,
>> case.in1 has -7.65.
>> O-s has -1.21, -0.30, mean is -0.75, while case.in1 has -1.46. Similarly
>> for Al-p and P-p.
>>
>
> Again, there should be l=0 E-parameters close to -7.24 and 1.21,
> respectively.
> In addition there should be definitely a second Al-s line at 0.30, since
> there are
> "real" Al 3s states in the valence region.
>
> I had mostly read about a supercell with one full core hole. Some of
>> these
>> are certainly cells where I do not want to build a larger supercell than I
>> have to. Is the HALF a core hole a better choice?
>>
>
> Are you interested in XPS or in XAS. This is a VERY different process
> where the
> excited electron leave the bulk or stays whithin the bulk.
>
> For XPS you are interested just in ONE number (Al-2p ionizationpotential)
> and
> Slaters transition state concept with half a core hole applies.
>
> For XAS you want to simulate a spectrum for a system with one core hole
> and an additional e- in
> the valence band. Use (at least for insulators) a full core hole.
>
>>
>> Do I understand correctly that whether I use a HALF core-hole or a full
>> one,
>> I then do minimization of the ionic positions again?
>>
>
> No. Electronic spectroscopy is a very fast process and the ions have no
> time to move
> around.
>
>
>> The user-guide says "The energy cut-off specified in lstart during init
>> lapw
>> (usually -6.0 Ry) defines the separation
>> into core- and band-states (the latter contain both, semicore and
>> valence)."
>> How do I get the Al 2p state into the core?
>> Do I have to change the cut-off and use .lcore, or is there some way to
>> move
>> just the Al 2p state into the core?
>>
>
> Besides an Energy (-X Ry), you can also specify a charge localization
> criterium
> (like 0.999), which will put all states with less charge inside sphere as
> valence.
> Checkout case.outputst to see how much charge each state has inside sphere:
> E-up(Ry) E-dn(Ry) Occupancy q/sphere core-state
> 1S -3.801989 -3.785331 1.00 1.00 0.9922 F
> 2S -0.236724 -0.003329 1.00 0.00 0.0675 F
>
>
>
>> PS There was no "reply" button in the archive except "Reply via email". I
>> could not find an answer as to how to reply to a post in either the Mail
>> Archive FAQ, or the WIEN mail archive.
>>
>> Thanks,
>> David
>>
>> ------------------------------------------------------------
>> ---------------
>> At Thu, 05 Mar 2015 22:41:38 -0800, Peter Blaha wrote
>> I think you have solved the problem very well.
>>
>> Due to the small P sphere and the fact, that P-s states are relatively
>> high in energy, the two linearization energies must be quite well
>> separated. (An alternative would have been to simply remove the second
>> l=0 line for P and change to "3" lines only:
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> 1 0.30 0.000 CONT 1
>> 1 -8.83 0.001 STOP 1
>> 0 -0.73 0.002 CONT 1
>>
>> Two more checks towards the "end of the scf cycle":
>> In case.scf2 you can find under the line :EPH and :EPL
>> the "mean" energy of the P-s states. If they are not close to -0.73
>> (thats where you expand P-s), change the corresponding input value.
>>
>> If the energy of the P-s states has gone down in energy at the end of the
>> scf-cycles, you may
>> checkout if you can go down with this second E-s input line from +6 back
>> to
>> 2.0
>> or even
>> back to 0.3 (sometimes such problems are temporary).
>>
>> PS: If you are interested in Al-2p XPS you should do Slaters transition
>> state !
>> Put Al 2p into the core and introduce HALF a core hole (compensated by a
>> background).
>> This gives much better core-eigenvalues that the plain DFT groundstate
>> eigenvalues,
>> typically lt. 1 % error as compared to 10 % error in comparison with
>> experiment.
>> In addition, final state screening effects are better accounted for.
>>
>>
>> Am 06.03.2015 um 00:44 schrieb David Olmsted:
>>
>>
>> Ghostbands: pushed energy range in case.in1 to 6.3, does this mean there
>> is
>> a problem?
>>
>> WIEN2k_14.2 (Release 15/10/2014)
>> Quad-Core AMD Opteron(tm) Processor 2378
>> Linux cluster
>> Intel 11.1 compilers with mkl.
>>
>> The purpose of my computation is to compare predicted XPS spectra for Al
>> 2p
>> electon
>> for different environments of the Al atom in the Al-P-O-H system.
>>
>> User: beginner! My first time using WEIN2k. Moderate amount of VASP
>> work.
>>
>> Issue: ghostbands
>>
>> GGA-PBE, 48 atoms, K-mesh 6x6x4, no shift. Not spin-polarized.
>> Initial cell and positions from relaxed GGA-PBE using VASP, same K-mesh.
>>
>> RMT from w2web StructGen (3% reduction)
>> H 0.63
>> O 1.17
>> P 1.34
>> Al 1.72
>>
>> RKmax 3.5 to get "effective RKmax" of 6.5 for O.
>>
>> rmt(min)*kmax = 3.50000
>> gmin = 11.11111
>> gmax = 20.00000
>>
>> ------- metavar_v.in0
>> TOT XC_PBE (XC_LDA,XC_PBESOL,XC_WC,XC_MBJ,XC_REVTPSS)
>>
>> NR2V IFFT (R2V)
>> 64 120 108 1.00 1 min IFFT-parameters, enhancement factor,
>> iprint
>> ---------
>>
>> For default -6 Ry cutoff for core states, charge was leaking out of RMT
>> sphere
>> for P 2p states. Final iteration in metavar_v.outputst:
>> 14 350
>> 14 1.85E-07 1.884765E+00 -8.645384E-01 -8.645386E-01
>> 1.72E-07
>> -1.67E-08 1.707034E-01 1.707034E-01
>> 1S -153.17082 -153.17082
>> 2S -12.78682 -12.78682
>> 2P* -9.19366 -9.19366
>> 2P -9.12626 -9.12626
>> 3S -1.02668 -1.02668
>> 3P* -0.40735 -0.40735
>> 3P -0.40342 -0.40342
>>
>> Cutoff set to -9.2 Ry. (Also tried leaving it at -6.0 Ry and touching
>> .lcore. Similar results.)
>>
>> ===============================================================
>> ---------------------------- Question -------------------------
>> ===============================================================
>>
>> With the original case.in1 file, had messages for the P atom, L=0:
>> (All these messages are from the first run of LAPW2.)
>>
>> metavar_v.scf2_1: QTL-B VALUE .EQ. 4951.54243 in Band of energy
>> -6.46139
>> ATOM= 2 L= 0
>>
>> increased 0.3 to 2.3 in case.in1, now:
>>
>> QTL-B VALUE .EQ. 1347.97207 in Band of energy -4.71553 ATOM= 2
>> L=
>> 0
>>
>> increased it 4.3
>>
>> QTL-B VALUE .EQ. 602.53449 in Band of energy -2.14697 ATOM= 2
>> L=
>> 0
>>
>> When I increased it to 6.3, no complaints.
>>
>> The initial scf run has completed with no warnings; the position
>> minimization is still running.
>>
>> In the mailing list search, there are suggestions to increase the (upper)
>> energy range to
>> 1.3 or "even 2.0" Ry. That makes me worry about the fact that I had to
>> increase it to a much
>> larger value. Does this mean something is going wrong?
>>
>> ------------------------- End of question ------------------------
>> =========== case.in1 =============================================
>> WFFIL EF=.1268392143 (WFFIL, WFPRI, ENFIL, SUPWF)
>> 3.5 10 4 (R-MT*K-MAX; MAX L IN WF, V-NMT
>> 0.30 4 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> 0 -7.65 0.001 STOP 1
>> 1 0.30 0.000 CONT 1
>> 1 -4.81 0.001 STOP 1
>> 0.30 4 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 1 0.30 0.000 CONT 1
>> 1 -8.83 0.001 STOP 1
>> 0 -0.73 0.002 CONT 1
>> 0 6.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 -1.46 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 -1.46 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 -1.46 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 -1.46 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 -1.46 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 -1.46 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 1 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> 0.30 1 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> 0.30 1 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> 0.30 1 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>> APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> K-VECTORS FROM UNIT:4 -12.2 1.5 250 emin / de (emax=Ef+de) /
>> nband #red
>>
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>>
> --
> -----------------------------------------
> Peter Blaha
> Inst. Materials Chemistry, TU Vienna
> Getreidemarkt 9, A-1060 Vienna, Austria
> Tel: +43-1-5880115671
> Fax: +43-1-5880115698
> email: pblaha at theochem.tuwien.ac.at
> -----------------------------------------
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