[Pw_forum] Cell optimization converges to unrealistic value
Giuseppe Mattioli
giuseppe.mattioli at ism.cnr.it
Wed Oct 10 16:30:56 CEST 2012
Dear Yuri
There are technical and physical reasons behind your unrealistic results.
technical:
> N 14.00700 N.pbe-van_ak.UPF
> H 1.00800 H.pbe-van_ak.UPF
> C 12.01100 C.pbe-van_ak.UPF
> Cu 63.54600 Cu.pbe-n-van_ak.UPF
> ecutwfc = 25 ,
In the case of ultrasoft pseudopotential ecutrho has to be indicated, having a value between
6*ecutwfc and 10*ecutwfc (convergence should be reached with respect to all such values, but I
perform satisfactorily converged CuPc calculations with the same pseudos by using
ecutwfc=35/ecutrho=280 cutoffs...)
> tot_charge = 0.000000,
> starting_magnetization(1) = 0.0,
> starting_magnetization(2) = 0.0,
> starting_magnetization(3) = 0.0,
> exxdiv_treatment = 'gygi-baldereschi' ,
useless keywords (in this case...). Starting_magnetization(4) = x with 0.0 < x < 1.0 is enough to
break the spin symmetry.
> nat = 33,
The copper phthalocyanine (CuPc) has 57 atoms. Have you checked the structure?
> ibrav = 6,
> celldm(1) = 20.11677,
> celldm(3) = 2.59367,
your molecules embedded into a tetragonal cell seems to be placed at a z distance of about 30 A from
its periodically repeated image... Check the exact use of the celldm(i) variables...
Physical:
Molecular crystals stay together because of dispersion interactions. As you are not using any kind
of dispersion correction, you will never obtain meaningful results on lattice parameters. There is
plenty of theoretical papers investigating the CuPc molecule. I suggest to start with them...
HTH
Giuseppe
On Monday 08 October 2012 11:09:41 Yura Vishnevskiy wrote:
> Dear QE users,
> I have a problem with cell optimization for one of my objects -- Copper
> phthalocyanine. It has layered structure and the distance between sheets
> must be around 3.3 Angstroms according to some experimental evidences.
> Using this value as an initial approximation I've started "vc-relax"
> calculation with pw.x from the latest version of the QE package (5.0).
> The calculation died several times after 15-20 optimization cycles with
> message
>
> "Error in routine scale_h (1):
> Not enough space allocated for radial FFT: try restarting with a
> larger cell_factor."
>
> and I restarted it using latest optimized parameters. During the
> optimization the distance between layers (parameter celldm(3)) got
> unrealistically small. Now it is around 1.3 Angstrom. What could be
> wrong with my input?
>
> &control
> calculation = 'vc-relax' ,
> restart_mode = 'from_scratch' ,
> prefix = 'cuph_3d_k444' ,
> verbosity = 'high' ,
> /
> &SYSTEM
> ibrav = 6,
> celldm(1) = 20.11677,
> celldm(3) = 2.59367,
> nat = 33,
> ntyp = 4,
> ecutwfc = 25 ,
> tot_charge = 0.000000,
> occupations = 'smearing' ,
> degauss = 0.02 ,
> smearing = 'gaussian' ,
> nspin = 2 ,
> starting_magnetization(1) = 0.0,
> starting_magnetization(2) = 0.0,
> starting_magnetization(3) = 0.0,
> starting_magnetization(4) = 0.5,
> exxdiv_treatment = 'gygi-baldereschi' ,
> /
> &ELECTRONS
> /
> &IONS
> /
> &CELL
> cell_dofree = 'xyz' ,
> /
> ATOMIC_SPECIES
> N 14.00700 N.pbe-van_ak.UPF
> H 1.00800 H.pbe-van_ak.UPF
> C 12.01100 C.pbe-van_ak.UPF
> Cu 63.54600 Cu.pbe-n-van_ak.UPF
> ATOMIC_POSITIONS angstrom
> N -0.002404756 1.949223697 -0.000000000
> N 1.949223697 -0.002404756 -0.000000000
> N 2.391389529 2.391389529 0.000000000
> N 8.271536989 2.397282537 -0.000000000
> N 8.695607152 -0.002619412 0.000000000
> N 2.397282537 8.271536989 0.000000000
> N -0.002619412 8.695607152 -0.000000000
> N 8.265225407 8.265225407 0.000000000
> H 5.350243681 8.115613628 0.000000000
> H 8.115613628 5.350243681 0.000000000
> H 5.350427438 2.574913054 0.000000000
> H 2.574913054 5.350427438 0.000000000
> C 1.116474541 2.759541645 0.000000000
> C 2.759541645 1.116474541 -0.000000000
> C 9.548405832 2.763398467 -0.000000000
> C 6.499236299 0.719922493 -0.000000000
> C 7.893740728 1.123273203 0.000000000
> C 5.329717857 1.479863666 0.000000000
> C 4.155377490 0.720022335 0.000000000
> C 2.763398467 9.548405832 0.000000000
> C 0.719922493 6.499236299 -0.000000000
> C 1.123273203 7.893740728 0.000000000
> C 1.479863666 5.329717857 -0.000000000
> C 0.720022335 4.155377490 -0.000000000
> C 6.497591960 9.961479852 0.000000000
> C 9.961479852 6.497591960 -0.000000000
> C 7.889717032 9.542180975 0.000000000
> C 9.542180975 7.889717032 -0.000000000
> C 5.330043432 9.207810550 0.000000000
> C 9.207810550 5.330043432 -0.000000000
> C 4.156498439 9.961968783 -0.000000000
> C 9.961968783 4.156498439 0.000000000
> Cu -0.017433297 -0.017433297 0.000000000
> K_POINTS automatic
> 4 4 4 0 0 0
>
>
> Thanks in advance,
> sincerely,
> Dr. Yury V. Vishnevskiy
> Lehrstuhl für Anorganische Chemie und Strukturchemie
> Universität Bielefeld
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
--
********************************************************
- Article premier - Les hommes naissent et demeurent
libres et ègaux en droits. Les distinctions sociales
ne peuvent être fondèes que sur l'utilitè commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et
imprescriptibles de l'homme. Ces droits sont la libertè,
la propriètè, la sùretè et la rèsistance à l'oppression.
********************************************************
Giuseppe Mattioli
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
v. Salaria Km 29,300 - C.P. 10
I 00015 - Monterotondo Stazione (RM)
Tel + 39 06 90672836 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>
More information about the users
mailing list