Hello QE community,
I am currently attempting to extract the kinetic energy contributions to the
total energies of different polymorphs of MgO.
I understand that we need to use the -pw2casino flag if we want our PWSCF
output to print a more detailed breakdown of the total energy in terms of its
contributions. This means that using the command:
mpirun -np 4 pw.x <project.in> project.out
will produce a project.out file which contains some text like this:
! total energy = -183.20894402 Ry
Harris-Foulkes estimate = -183.20894409 Ry
estimated scf accuracy < 0.00000009 Ry
total all-electron energy = -551.326109 Ry
The total energy is the sum of the following terms:
one-electron contribution = -85.45759185 Ry
hartree contribution = 47.93001020 Ry
xc contribution = -25.22704816 Ry
ewald contribution = -95.91150866 Ry
one-center paw contrib. = -24.54280555 Ry
while adding the -pw2casino flag and running:
mpirun -np 4 pw.x -pw2casino <project.in> project.out
will print the original lines above, as well as additional lines like:
Energies determined by pw2casino tool
-------------------------------------
Kinetic energy 21.442363717309750 au = 42.884727434619499
Ry
Local energy -84.609446621660297 au = -169.21889324332059
Ry
Non-Local energy 20.438286977076853 au = 40.876573954153706
Ry
Ewald energy -47.955754330605572 au = -95.911508661211144
Ry
xc contribution -12.613524077939315 au = -25.227048155878631
Ry
hartree energy 23.965005100370561 au = 47.930010200741123
Ry
Total energy -79.333069235448022 au = -158.66613847089604
Ry
>From the above output lines, we can see that the total energies (-183.20894402
>Ry and -158.66613847089604 Ry) are pretty terribly mismatched. I find that
>this mismatch occurs when using either PWSCF v5.0.2 and PWSCF v6.0. When I was
>using PWSCF v6.0, quantum-espresso actually prints an "Energy mismatch error"
>(I'd paste the error below but my laptop, which runs v6.0, is currently in the
>shop), so at least it recognizes that something is wrong.
I've tried looking through some other threads and attempted to apply fixes that
worked for other people, such as adding the following line:
assume_isolated = 'mp'
to my &CONTROL in my input file (source:
http://lists.quantum-espresso.org/pipermail/users/2015-April/032059.html), but
nothing so far has worked.
Does anyone have any idea what the issue is and how to resolve it? Because
with the demonstrated mismatch in total energies, I do not have faith in the
kinetic energy value that is output. If this helps, I am using the following
pseudopotentials:
file Mg.pbe-spnl-kjpaw_psl.1.0.0.UPF: wavefunction(s) 2P renormalized
file O.pbe-nl-kjpaw_psl.1.0.0.UPF: wavefunction(s) 2S 2P renormalized
and below is my input file for MgO in a CsCl-type crystalline arrangement
(which generated the energy values I gave above, using PWSCF v5.0.2):
&CONTROL
calculation = "scf"
max_seconds = 8.64000e+04
outdir = "./"
prefix = "MgO_CsCl"
pseudo_dir = "/home/davidho/.burai/.pseudopot"
title = "Working MgO CsCl Structure(SCF)"
wf_collect = .TRUE.
/
&SYSTEM
a = 2.65994e+00
degauss = 1.00000e-02
ecutrho = 2.00000e+03
ecutwfc = 2.00000e+02
ibrav = 1
nat = 2
ntyp = 2
occupations = "fixed"
smearing = "gaussian"
assume_isolated = 'mp'
/
&ELECTRONS
conv_thr = 1.00000e-06
electron_maxstep = 200
mixing_beta = 7.00000e-01
startingpot = "atomic"
startingwfc = "atomic+random"
/
K_POINTS {automatic}
10 10 10 0 0 0
ATOMIC_SPECIES
Mg 24.30500 Mg.pbe-spnl-kjpaw_psl.1.0.0.UPF
O 15.99940 O.pbe-nl-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS {angstrom}
Mg 0.000000 0.000000 0.000000
O 1.329970 1.329970 1.329970
Any help and further insight into both the problem with and/or the method of
energy decomposition would be greatly appreciated.
Thank you,
Wai-Ga David Ho, Department of Physics at Florida State University
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