[Wien] How to get accurate GAP using BJ or mBJ methods?
Peter Blaha
pblaha at theochem.tuwien.ac.at
Tue Mar 1 10:51:06 CET 2016
> I have another question.In some papers, they said ‘The potential and charge density in the muffin-tin (MT) spheres are expanded in spherical harmonics with lmax = 8 and non-spherical components up to lmax = 6.’
>
> I don’t know how to set different lmax value during the calculation. Can you tell me how to do ?
This is a bit sloppy/wrong formulation in these papers, as it makes no
sense to talk about in a "charge density expansion" about different l
values. Everything beyond l=0 is "non-spherical".
We can set the max. l-expansion for the wave functions in the spherical
part of the hamiltonian <psi|V_sph|psi>, which is by default=10 in
case.in1 (second line). Probably they reduced it to 8 in this paper
(don't go below 8)
We can also set the max l-expansion in the wf. for the nonspherical part
of H <psi|V_nsph|psi>, and this is 4 by default (again second line
of in1).
Larger values will lead to much longer cpu time.
The expansion of charge density and potential is set in case.in2, in the
LM-list. By default this goes to L=6
>
>
> Date: Mon, 29 Feb 2016 18:40:25 +0100
> From: tran at theochem.tuwien.ac.at
> To: wien at zeus.theochem.tuwien.ac.at
> Subject: Re: [Wien] How to get accurate GAP using BJ or mBJ methods?
>
> The fundamental problem of DFT is to be an approximate method whatever
> is the xc functional/potential that is used.
>
> Anyway, if you really need band structure for your compounds with correct
> band gap, then you can empirically adjust the parameter c of the mBJ
> potential until the desired band gaps is obtained. For this, you need
> to create the file case.in0abp.
> For instance if you want to fix c to 1.2, the case.in0abp should be like
> this (see Sec. 4.5.9 of the UG):
> 1.2
> 0.0
> 1.0
>
> F. Tran
>
> On Mon, 29 Feb 2016, JingQun wrote:
>
>>
>> Dear all,
>>
>> I am running wien 14.2 on a machine with operating system centos 6.5, fortran compiler ifort.
>>
>> I want to calculate the electronic structures of borates （such as BBO, KBBF, LBO, and so on）and get accurate GAP using BJ or mBJ methods. During the calculation, I have encountered some problems. They are:
>>
>> 1, Take KBBF for example. The bandgap of KBBF is 8.0 eV (the UV cutoff edge is about 155 nm). During the calculation, the unit-cell parameters and atomic coordinates were obtained from XRD, and the RMT were set as K (2.50), Be(1.28), B(1.19), O(1.38)
>> F(1.56). The core electron states were separated from the valence states by -8.0 Ry, and the Rkmax was set as 5.0. The Irreducible Brillouin Zon was sampled at 500 k-points without shifted meshes, and the convergent condition for SCF was set as 10E(-5). In
>> order to get accurate GAP as described elsewhere, a mBJ method was used. While unlike many other successful example, the bandgap obtained is either larger or smaller than the experimental values. That is to say, when I chose ‘Original mBJ values (Tran,Blaha
>> PRL102,226401)’to calculate, the GAP of KBBF is about 11.504 eV, much larger than the experimental values (8.0 eV), while when I chose ‘Unmodified BJ potential (Becke,Johnson J.Chem.Phys 124,221101’, the result is 7.301 eV, smaller than experimental values.
>> Can anyone kindly tell me how to get accurate bandgap value of borates ?
>>
>> PS: The KBBF.struct, KBBF.in1c, KBBF.in2c were added as attachment.
>>
>> KBBF.struct
>>
>> blebleble
>> R LATTICE,NONEQUIV.ATOMS 5 155 R32
>> MODE OF CALC=RELA unit=bohr
>> 8.364065 8.364065 35.454261 90.000000 90.000000120.000000
>> ATOM -1: X=0.00000000 Y=0.00000000 Z=0.00000000
>> MULT= 1 ISPLIT= 4
>> K NPT= 781 R0=.000050000 RMT= 2.50000 Z: 19.00000
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -2: X=0.72172000 Y=0.72172000 Z=0.72172000
>> MULT= 2 ISPLIT= 4
>> -2: X=0.27828000 Y=0.27828000 Z=0.27828000
>> F NPT= 781 R0=.000100000 RMT= 1.56 Z: 9.00000
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -3: X=0.80242000 Y=0.80242000 Z=0.80242000
>> MULT= 2 ISPLIT= 4
>> -3: X=0.19758000 Y=0.19758000 Z=0.19758000
>> Be NPT= 781 R0=.000100000 RMT= 1.28 Z: 4.00000
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -4: X=0.50000000 Y=0.19045000 Z=0.80955000
>> MULT= 3 ISPLIT= 8
>> -4: X=0.80955000 Y=0.50000000 Z=0.19045000
>> -4: X=0.19045000 Y=0.80955000 Z=0.50000000
>> O NPT= 781 R0=.000100000 RMT= 1.38 Z: 8.00000
>> LOCAL ROT MATRIX: 0.0000000 0.5000000 0.8660254
>> 0.0000000-0.8660254 0.5000000
>> 1.0000000 0.0000000 0.0000000
>> ATOM -5: X=0.50000000 Y=0.50000000 Z=0.50000000
>> MULT= 1 ISPLIT= 4
>> B NPT= 781 R0=.000100000 RMT= 1.19 Z: 5.00000
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> 6 NUMBER OF SYMMETRY OPERATIONS
>> -1 0 0 0.00000000
>> 0 0-1 0.00000000
>> 0-1 0 0.00000000
>> 1
>> 0-1 0 0.00000000
>> -1 0 0 0.00000000
>> 0 0-1 0.00000000
>> 2
>> 0 0-1 0.00000000
>> 0-1 0 0.00000000
>> -1 0 0 0.00000000
>> 3
>> 0 1 0 0.00000000
>> 0 0 1 0.00000000
>> 1 0 0 0.00000000
>> 4
>> 0 0 1 0.00000000
>> 1 0 0 0.00000000
>> 0 1 0 0.00000000
>> 5
>> 1 0 0 0.00000000
>> 0 1 0 0.00000000
>> 0 0 1 0.00000000
>> 6
>>
>> KBBF.in1c
>>
>> WFFIL EF=-.100583812400 (WFFIL, WFPRI, ENFIL, SUPWF)
>> 5.00 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 -2.30 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 -1.08 0.002 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global APW/LAPW)
>> 0 -1.90 0.002 CONT 1
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> 0.30 2 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> 0 -7.51 0.001 STOP 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 2 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global APW/LAPW)
>> 0 0.30 0.000 CONT 1
>> 1 0.30 0.000 CONT 1
>> K-VECTORS FROM UNIT:4 -11.0 1.5 54 emin / de (emax=Ef+de) / nband
>>
>> KBBF.in2c
>>
>> TOT (TOT,FOR,QTL,EFG,FERMI)
>> -14.00 52.00 0.50 0.05 1 EMIN, NE, ESEPERMIN, ESEPER0, iqtlsave
>> TETRA 0.000 (GAUSS,ROOT,TEMP,TETRA,ALL eval)
>> 0 0 2 0 -3 3 4 0 4 3 -5 3 6 0 6 3 6 6
>> 0 0 1 0 2 0 3 0 3 3 -3 3 4 0 4 3 -4 3 5 0 5 3 -5 3 6 0 6 3 -6 3 6 6 -6 6
>> 0 0 1 0 2 0 3 0 3 3 -3 3 4 0 4 3 -4 3 5 0 5 3 -5 3 6 0 6 3 -6 3 6 6 -6 6
>> 0 0 1 0 2 0 2 2 -2 2 3 0 3 2 -3 2 4 0 4 2 -4 2 4 4 -4 4 5 0 5 2 -5 2 5 4 -5 4 6 0 6 2 -6 2 6 4 -6 4 6 6 -6 6
>> 0 0 2 0 -3 3 4 0 4 3 -5 3 6 0 6 3 6 6
>> 14.00 GMAX
>> NOFILE FILE/NOFILE write recprlist
>>
>> 2, In some papers, they said ‘The potential and charge density in the muffin-tin (MT) spheres are expanded in spherical harmonics with lmax = 8 and non-spherical components up to lmax = 6.’I don’t know how to set different lmax value during the calculation.
>> Can anyone tell me how to do ?
>>
>> Thanks very much.
>>
>> Yours
>>
>> Qun Jing
>>
>>
>>
>>
>>
>
>
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--
P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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