[gpaw-users] Funny electronic band structure

[Darío Fdez-Pello Lois]

Dear Jens Jørgen, dear all,

Yes, the primitive unit cell solved the inconsistency!

Many thanks to you all!!

Cheers,

   Darío.

2015-02-04 14:12 GMT+01:00 Jens Jørgen Mortensen <jensj at fysik.dtu.dk>:

> On 02/03/2015 10:59 AM, Darío Fdez-Pello Lois wrote:
>
>> Dear all,
>>
>> Thanks for your replies, indeed it should be a colon after 'size', I
>> mistyped it somehow.
>>
>> The requested figures are attached, please let me say that Mo_band.png
>> comes from the QE and ELK calculations while MoBandstructure.png comes from
>> GPAW.
>>
>
> It looks like you have a cubic cell with two atoms.  Try with the
> primitive unit cell:
>
> >>> from ase.lattice import bulk
> >>> mo = bulk('Mo')
>
> See here:
>
> https://wiki.fysik.dtu.dk/ase/ase/structure.html#ase.lattice.bulk
>
> Jens Jørgen
>
>
>> In addition, here are the scripts:
>> -------SCF
>> import numpy as NP
>> from ase.lattice.cubic import BodyCenteredCubic
>> from gpaw import GPAW,PW,MethfesselPaxton,Mixer
>> from ase.io <http://ase.io> import read
>>
>> k = 10
>> ecut = 600
>> N = 1
>> configs = read('MoStrain.traj@:')
>> aa = NP.array([config.cell[0, 0] for config in configs])
>> a = aa[-1]
>>
>> mo = BodyCenteredCubic(size=(N,N,N),symbol='Mo',latticeconstant=a)
>> mo.calc = GPAW(mode=PW(ecut), xc='PBE', kpts={'size': (k,k,k),'gamma':
>> True}, setups={'Mo': '6'}, occupations=MethfesselPaxton(0.01),
>> mixer=Mixer(0.1, 1, 100), txt='bulk.txt')
>> mo.get_potential_energy()
>> mo.calc.write('bulk.gpw')
>>
>> --------BAND
>> import numpy as NP
>> from ase.io <http://ase.io> import read, write
>>
>> from ase.lattice.cubic import BodyCenteredCubic
>> from ase.dft.kpoints import ibz_points, get_bandpath
>> from gpaw import GPAW, PW, MethfesselPaxton
>> import matplotlib
>> matplotlib.use('Agg')
>> import matplotlib.pyplot as plt
>>
>> num_bands=12
>>
>> calc = GPAW('bulk.gpw', fixdensity=True, usesymm=None,
>> convergence={'bands': num_bands}, maxiter=600, txt='band.txt')
>> points = ibz_points['bcc']
>> G = points['Gamma']
>> H = points['H']
>> N = points['N']
>> P = points['P']
>> kpts, x, X = get_bandpath([G, H, N, G, P], calc.atoms.cell, 200)
>> calc.set(kpts=kpts)
>> calc.get_potential_energy()
>> e_kn = NP.array([calc.get_eigenvalues(k) for k in range(len(kpts))])
>>
>> # Plot the band structure
>>
>> e_f = calc.get_fermi_level()
>> e_kn -= e_f
>> emin = -10 #e_kn.min() - 1.0
>> emax = 10 #e_kn[:, num_bands].max() + 1.0
>>
>> plt.figure(figsize=(5, 6))
>> for n in range(num_bands):
>>     plt.plot(x, e_kn[:, n])
>> for p in X:
>>     plt.plot([p, p], [emin, emax], 'k-')
>> plt.plot([0, X[-1]], [0, 0], 'k-')
>> plt.xticks(X, ['$%s$' % n for n in ['\Gamma', 'H', 'N', '\Gamma', 'P']])
>> plt.axis(xmin=0, xmax=X[-1], ymin=emin, ymax=emax)
>> plt.xlabel('k-vector')
>> plt.ylabel('E - E$_F$ (eV)')
>> plt.title('Bandstructure of Mo')
>> plt.savefig('MoBandstructure.png')
>>
>> --------------------
>> ​END of scripts​
>>
>>
>> ​Best regards,
>>
>>    Darío​
>>
>>
>> 2015-02-03 8:19 GMT+01:00 Jussi Enkovaara <jussi.enkovaara at csc.fi
>> <mailto:jussi.enkovaara at csc.fi>>:
>>
>>
>>     Hi Dario,
>>     could you be a bit more specific what's wrong with the band
>>     stucture (preferrably with a picture of correct / incorrect one),
>>     e.g are some bands fine but others not?
>>
>>     In principle, your script below looks fine, but could you also
>>     provide the full scripts for SCF and band structure calculations?
>>
>>     Best regards,
>>     Jussi Enkovaara
>>
>>
>>     On 2015-02-03 00:38, Darío Fdez-Pello Lois wrote:
>>
>>         Dear all,
>>
>>         My question is related to the calculation of the electronic
>>         band structure
>>         of molybdenum, which I was successfully able to reproduce both
>>         using a full
>>         potential code (ELK) and a plane wave one (Quantum Espesso).
>>         Unfortunately,
>>         the same doesn't happen when I use GPAW (with PW mode)
>>         resulting a quite
>>         different structure.
>>         Here are the relevant (I guess) lines, of course the
>>         obligatory parameter's
>>         convergence were peviouslly done:
>>
>>         [ ... ]
>>         mo=BodyCenteredCubic(size(N,N,N),symbol='Mo',latticeconstant=a)
>>         mo.calc = GPAW(mode=PW(ecut),
>>                xc='PBE',
>>                kpts={'size'(k,k,k),'gamma': True},
>>                setups={'Mo': '6'},
>>                occupations=MethfesselPaxton(0.01),
>>                mixer=Mixer(0.1, 1, 100),
>>                txt='bulk.txt')
>>         [ ... ]
>>
>>         thereafter I run the band structure script similar to the one
>>         given in the
>>         tutorial (with obvious changes: bcc instead of fcc, etc.)
>>
>>         I am very confused at this point and I hope some of you would
>>         kindly give
>>         me some insight.
>>
>>         Best,
>>
>>            Darío.
>>
>>
>>
>>
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>>
>>
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