[QE-users] oscillations in G(V) diagram
Jakob Kraus
jakob.kraus at physik.tu-freiberg.de
Sun Nov 6 16:40:27 CET 2022
Dear QE users,
thank you very much for your comments.
To clarify: I am indeed trying to work with the QHA, and the diagrams
with the oscillations I talked about show F(V,T) + pV as a function of V
for a given temperature.
The system in the input files is a cubic insulator, and I calculate the
phonon contributions in F(V,T) with the help of the phonon DOS as
generated by successive application of
ph.x, q2r.x, and matdyn.x. The combination of total energy and phononic
contributions is done with the help of the ASE CrystalThermo functionality.
The calculations for the series of volumes currently use the same
rescaled cubic unit cell, with matching rescaled atomic positions.
I will try the cell_dofree='shape' option and keep you updated. If you
have further suggestions, feel free to add!
Best regards,
Jakob
Am 06.11.2022 um 12:00 schrieb users-request at lists.quantum-espresso.org:
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> Today's Topics:
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> 1. oscillations in G(V) diagrams (Jakob Kraus)
> 2. Re: oscillations in G(V) diagrams (Lorenzo Bastonero)
> 3. Re: oscillations in G(V) diagrams (Lorenzo Paulatto)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 4 Nov 2022 09:20:27 +0100
> From: Jakob Kraus <jakob.kraus at physik.tu-freiberg.de>
> To: users at lists.quantum-espresso.org
> Subject: [QE-users] oscillations in G(V) diagrams
> Message-ID:
> <68c7ecda-68e4-bf8b-68af-ea7d030635f8 at physik.tu-freiberg.de>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Dear QE users,
>
>
> I am trying to calculate heat capacities, and to this end, I have
> calculated the Gibbs energy as a function of volume
>
> at several temperatures in a range of 0-700 K.
>
> However, the functions that result from this do not show a single
> minimum, but rather a whole lot of oscillations, which
>
> seem to originate from the phonons, since the E(V) diagram at 0 K shows
> a single minimum as expected.
>
> I am thankful for any help you can offer with getting rid of these
> oscillations.
>
> I have attached input files and some plots to showcase the problem.
>
>
> Best regards,
>
>
> Jakob Kraus, TU Freiberg
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> &input
> fildyn = 'matdyn'
> zasr = 'crystal'
> flfrc = 'force.fc'
> /
> -------------- next part --------------
> &CONTROL
> calculation = 'scf'
> title = 'Zr_BH4_4_v95'
> verbosity = 'high'
> restart_mode = 'from_scratch'
> tstress = .true.
> tprnfor = .true.
> outdir = './'
> prefix = 'espresso'
> pseudo_dir = '/home/kraus/pslibrary_pp/PBE_PAW'
> /
> &SYSTEM
> ibrav = 1
> ecutwfc = 120
> ecutrho = 960
> occupations = 'fixed'
> nspin = 1
> ntyp = 3
> nat = 21
> celldm(1) = 11.718963054402725
> /
> &ELECTRONS
> electron_maxstep = 300
> conv_thr = 1e-10
> mixing_beta = 0.7
> /
>
> ATOMIC_SPECIES
> Zr 91.224 Zr.pbe-spn-kjpaw_psl.1.0.0.UPF
> B 10.81 B.pbe-n-kjpaw_psl.1.0.0.UPF
> H 1.008 H.pbe-kjpaw_psl.1.0.0.UPF
>
> K_POINTS automatic
> 2 2 2 0 0 0
>
> ATOMIC_POSITIONS angstrom
> Zr 3.1007040770 3.1007040770 3.1007040770
> B 4.4131080846 1.7883000693 1.7883000693
> B 1.7883000693 4.4131080846 1.7883000693
> B 1.7883000693 1.7883000693 4.4131080846
> B 4.4131080846 4.4131080846 4.4131080846
> H 3.2091046915 1.6105056976 1.6105056976
> H 2.9923034624 4.5909024564 1.6105056976
> H 2.9923034624 1.6105056976 4.5909024564
> H 3.2091046915 4.5909024564 4.5909024564
> H 1.6105056976 3.2091046915 1.6105056976
> H 1.6105056976 2.9923034624 4.5909024564
> H 4.5909024564 2.9923034624 1.6105056976
> H 4.5909024564 3.2091046915 4.5909024564
> H 1.6105056976 1.6105056976 3.2091046915
> H 4.5909024564 1.6105056976 2.9923034624
> H 1.6105056976 4.5909024564 2.9923034624
> H 4.5909024564 4.5909024564 3.2091046915
> H 5.0910460240 1.1103621300 1.1103621300
> H 1.1103621300 5.0910460240 1.1103621300
> H 1.1103621300 1.1103621300 5.0910460240
> H 5.0910460240 5.0910460240 5.0910460240
>
> -------------- next part --------------
> phdos Zr_BH4_4
> &INPUTPH
> tr2_ph = 1.D-14
> prefix = 'espresso'
> outdir = './'
> fildyn = 'matdyn'
> ldisp = .true.
> nq1 = 3
> nq2 = 3
> nq3 = 3
> /
> -------------- next part --------------
> &input
> asr = 'crystal'
> flfrc = 'force.fc'
> dos = .true.
> fldos = 'matdyn.dos'
> deltaE = 1
> nk1 = 20
> nk2 = 20
> nk3 = 20
> /
>
> ------------------------------
>
> Message: 2
> Date: Sat, 5 Nov 2022 16:55:49 +0100
> From: Lorenzo Bastonero <lbastone at uni-bremen.de>
> To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
> Subject: Re: [QE-users] oscillations in G(V) diagrams
> Message-ID: <1FAE10D0-D7D7-442A-937C-A5ADD90C107B at uni-bremen.de>
> Content-Type: text/plain; charset="us-ascii"
>
> Dear Jakob,
>
> Do you mean the Helmoltz free energy (F)?
>
> As by definition, the Gibbs free energy (G) does not depend upon volume, but on pressure and temperature.
> At p=0, then they are the same, but notice always that:
>
> G(p,T) = min_{V}[F(V, T)+pV]
>
> Thus, at p=0, you still need to take the minimum of F at the fixed temperature.
>
> Moreover, I guess you are using the quasi-harmonic approximation. There exist several flavours. Unless your system is isotropic, scaling the volume isotropically can be a source of error (due to a physical assumption, not due to the numerics).
>
> Best,
> Lorenzo Bastonero
>
> ********************************
> Lorenzo Bastonero
>
> PhD Student
> U Bremen Excellence Chair,
> Bremen Center for Computational Materials Science,
> and MAPEX Center for Materials and Processes
>
> University of Bremen
> Faculty of Production Engineering
> TAB-Building, Room 3.32
> Am Fallturm 1
> 28359 Bremen, DE
>
> http://www.hmi.uni-bremen.de/
>
>> Il giorno 4 nov 2022, alle ore 09:20, Jakob Kraus <jakob.kraus at physik.tu-freiberg.de> ha scritto:
>>
>> Dear QE users,
>>
>>
>> I am trying to calculate heat capacities, and to this end, I have calculated the Gibbs energy as a function of volume
>>
>> at several temperatures in a range of 0-700 K.
>>
>> However, the functions that result from this do not show a single minimum, but rather a whole lot of oscillations, which
>>
>> seem to originate from the phonons, since the E(V) diagram at 0 K shows a single minimum as expected.
>>
>> I am thankful for any help you can offer with getting rid of these oscillations.
>>
>> I have attached input files and some plots to showcase the problem.
>>
>>
>> Best regards,
>>
>>
>> Jakob Kraus, TU Freiberg
>> <G_Zr_BH4_0.0.png><E_Zr_BH4.png><espresso.qi><espresso.pwi><espresso.phi><espresso.mdi>_______________________________________________
>> The Quantum ESPRESSO community stands by the Ukrainian
>> people and expresses its concerns about the devastating
>> effects that the Russian military offensive has on their
>> country and on the free and peaceful scientific, cultural,
>> and economic cooperation amongst peoples
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
>> users mailing list users at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
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> ------------------------------
>
> Message: 3
> Date: Sat, 5 Nov 2022 22:09:31 +0100
> From: Lorenzo Paulatto <lorenzo.paulatto at cnrs.fr>
> To: <users at lists.quantum-espresso.org>
> Subject: Re: [QE-users] oscillations in G(V) diagrams
> Message-ID: <76693ba3-d502-65e2-005a-5a9b9aab1922 at cnrs.fr>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Hello Jakob,
>
> you do not give much detail about what you are doing. As said, QHA is
> effective when dealing with one degree of freedom (i.e. cubic
> semiconductor) but harder to use in any other case. Are you doing a
> constant-volume variable-cell relax (aka cell_dofree='shape') for a
> series of volumes? And then computing for each volume the Helmholtz free
> energy (from the phonons directly or from the dos)? Are you doing this
> your self by hand or using one of the available QHA software packages?
>
> The oscillations could be an honest bug, or a difficult integration of
> the DOS.
>
> cheers
>
>
> On 04/11/2022 09:20, Jakob Kraus wrote:
>> Dear QE users,
>>
>>
>> I am trying to calculate heat capacities, and to this end, I have
>> calculated the Gibbs energy as a function of volume
>>
>> at several temperatures in a range of 0-700 K.
>>
>> However, the functions that result from this do not show a single
>> minimum, but rather a whole lot of oscillations, which
>>
>> seem to originate from the phonons, since the E(V) diagram at 0 K
>> shows a single minimum as expected.
>>
>> I am thankful for any help you can offer with getting rid of these
>> oscillations.
>>
>> I have attached input files and some plots to showcase the problem.
>>
>>
>> Best regards,
>>
>>
>> Jakob Kraus, TU Freiberg
>>
>> _______________________________________________
>> The Quantum ESPRESSO community stands by the Ukrainian
>> people and expresses its concerns about the devastating
>> effects that the Russian military offensive has on their
>> country and on the free and peaceful scientific, cultural,
>> and economic cooperation amongst peoples
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
>> users mailing listusers at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
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