Just to clarify: You are doing MD, not a geometry optimisation, and you
are surprised that the forces don't go to zero? What are you trying to
find? For a minimum energy structure, you need a geometry optimisation.
In an MD simulation the total (potential+kinetic) energy should remain
constant (depending on your ensemble...), but the forces will vary.
Herbert
On 22/11/2013 08:58, Максим Арсентьев wrote:
Dear Sebastian!
My calculations convverge at each MD cycle (about 300-400 SCF cycles),
but max force oscillate (about 0.1-0.04 eV/anstrom) and I can not finish
MD, and am already at 63 cycle and the calculation cycle is still going,
although the system is quite large and contains 47 atoms. My counter
question to all: does this oscillation of forces normal?
I would like to strict DM.Tolerance to 0.00001 (it is VERY important to
accurate calculation of forces) and to limit MD.MaxCGDispl .
Best Wishes,
Maxim
2013/11/21 Sebastian Caicedo Davila
<sebastian.caic...@correounivalle.edu.co
<mailto:sebastian.caic...@correounivalle.edu.co>>
Hello Diana!!
Thanks a lot for your suggestion! I'll give it a try and maybe I'll
be bothering you again, if it is not an imposition, of course.
Gracias de nuevo, y saludos desde tu tierra!
Sebastian Caicedo Davila
Bionanoelectronics Research Group
School of electrical and electronics engineering
Universidad del Valle
Cali - Colombia.
On Nov 21, 2013, at 11:02 AM, <d.otalv...@utwente.nl
<mailto:d.otalv...@utwente.nl>> <d.otalv...@utwente.nl
<mailto:d.otalv...@utwente.nl>> wrote:
Hello Sebastian,
I have had similar problems with convergence of the scf cycle.
They were solved when I changed from Pulay mixing to Broyden
mixing for the charge density.
Usually if something doesn't converge in 250 cycles, it probably
never will. Also you can play with the DM.Tolerance. For very
difficult systems I set it to 0.0008 and then restart from that DM
file with a stringer convergence criterion.
Here is the settings I am using for my calculations:
#--------------------Convergence of SCF-------------------------------
MeshCutoff 200.0 Ry # Default value PW cutoff
for grid
MaxSCFIterations 250 # Maximum number of SCF iter
DM.NumberBroyden 3
DM.MixingWeight 0.01 # New DM amount for next
SCF cycle
DM.Tolerance 0.0001 # Tolerance in maximum
difference
DM.UseSaveDM .false. # to use continuation files
DM.NumberKick 100
DM.KickMixingWeight 0.01
#----------------------------------
Suerte!
PS: yo tambien soy caleña!
Diana M. Otálvaro
PhD Candidate
Computational Material Science
MESA+ Institute of Nanotechnology
University of Twente.
Enschede, Nederland
------------------------------------------------------------------------
*From:*siesta-l-requ...@uam.es <mailto:siesta-l-requ...@uam.es>
[siesta-l-requ...@uam.es <mailto:siesta-l-requ...@uam.es>] on
behalf of Максим Арсентьев [ars21031...@gmail.com
<mailto:ars21031...@gmail.com>]
*Sent:*Wednesday, November 20, 2013 7:29 AM
*To:*siesta-l@uam.es <mailto:siesta-l@uam.es>
*Subject:*Re: [SIESTA-L] Convergence problem on heterostructure.
I forgot to tell you - besides DM.MixingWeight 0.05 I also set
PAO.EnergyShift to 65 meV as
herehttp://www.nature.com/nnano/journal/v7/n9/extref/nnano.2012.127-s2.txt .
Best wishes,
Dr. Maxim Arsent'ev
Laboratory of inorganic synthesis
Institute of Silicate Chemistry of RAS
2013/11/18 Mahmoud Hammouri<m...@nmsu.edu <mailto:m...@nmsu.edu>>
You could also try to increase the non-equilibrium contour points.
Mahmoud
On Nov 18, 2013, at 11:22, "Sebastián Cauce do Dávila"
<sebastian.caic...@correounivalle.edu.co
<mailto:sebastian.caic...@correounivalle.edu.co>> wrote:
Thank you very much for your suggestion. I will give it a try!
Sebastián Caicedo Dávila
Bionanoelectronics research group
School of electrical and electronics engineering
Universidad del Valle
Cali - Colombia
On 18/11/2013, at 11:50, Максим Арсентьев
<ars21031...@gmail.com <mailto:ars21031...@gmail.com>> wrote:
I also try some siesta only six months, but for a more
heterogeneous structure I noticed that the reduction
DM.MixingWeight reduces oscillations in convergence, so try
to play with it (decrease DM.MixingWeight). See
http://www.nature.com/nnano/journal/v7/n9/extref/nnano.2012.127-s2.txt
Maybe someone will tell something else.
2013/11/18 Sebastian Caicedo
D.<sebastian.caic...@correounivalle.edu.co
<mailto:sebastian.caic...@correounivalle.edu.co>>
Dear Siesta/Transiesta users,
I've been using the software for a couple months and
made some calculations of InAs and InP unit cell quite
successfully. Now I intend to work on transiesta
calculations of a heterostructure of both these
materials (InAs bulk with InP barriers). As a first
approach I want to simulate a couple of InAs unit cells
and the barriers shall be unit cells of InP, just to get
a qualitative idea. The electrodes .TSHS files were
obtained from the previous calculations of the InAs unit
cell. I wanted first to run a siesta calculation of the
whole heterostructure, so I can take a look at the
eigenvalues and define a correct value for the parameter
TS.ComplexContour.Emin, as suggested in the manual.
The structure has 120 atoms and I'm using LDA
Pseudopotentials, obtained from the siesta webpage. (In
Pseudo includes semicore electrons, so we have enough
electrons to build a zinc-blende structure). The issue
is that after 1000 SCF steps, the energy doesn't
converge at all. I'm doing a Gamma-point calculation,
but even when I make the k-grid 1x1x15 it doesn't work
either.
I used the same MeshCutoff as for the individual
materials unit cell an 200Ry and I increased the Energy
Shift, so the calculation would be a bit faster though
less precise.
I attach the Input (INPUT.fdf, STRUCTURE.fdf) and output
files.
I would really appreciate any suggestions.
sincerely
Sebastian Caicedo Davila
Bionanoelectronics Group
School of Electrical and Electronics Engineering
Universidad del Valle
Cali-Colombia
--
Best wishes,
Dr. Maxim Arsent'ev
Laboratory of inorganic synthesis
Institute of Silicate Chemistry of RAS
--
Best wishes,
Dr. Maxim Arsent'ev
Laboratory of inorganic synthesis
Institute of Silicate Chemistry of RAS
--
Best wishes,
Dr. Maxim Arsent'ev
Laboratory of inorganic synthesis
Institute of Silicate Chemistry of RAS
--
Herbert Fruchtl
Senior Scientific Computing Officer
School of Chemistry, School of Mathematics and Statistics
University of St Andrews
--
The University of St Andrews is a charity registered in Scotland:
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