I'm doing geometry optimisation if I correctly set it (as I understand it's by default)
Best Wishes, Maxim. 2013/11/22 Herbert Fruchtl <[email protected]> > 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 >> <[email protected] >> <mailto:[email protected]>> >> >> >> 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, <[email protected] >> <mailto:[email protected]>> <[email protected] >> <mailto:[email protected]>> 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:*[email protected] <mailto:[email protected]> >>> [[email protected] <mailto:[email protected]>] on >>> >>> behalf of Максим Арсентьев [[email protected] >>> <mailto:[email protected]>] >>> *Sent:*Wednesday, November 20, 2013 7:29 AM >>> *To:*[email protected] <mailto:[email protected]> >>> *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<[email protected] <mailto:[email protected]>> >>> >>> >>> You could also try to increase the non-equilibrium contour >>> points. >>> >>> Mahmoud >>> >>> >>> On Nov 18, 2013, at 11:22, "Sebastián Cauce do Dávila" >>> <[email protected] >>> <mailto:[email protected]>> 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 >>>> <[email protected] <mailto:[email protected]>> 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.<[email protected] >>>>> <mailto:[email protected]>> >>>>> >>>>> >>>>> 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: > No SC013532 > -- Best wishes, Dr. Maxim Arsent'ev Laboratory of inorganic synthesis Institute of Silicate Chemistry of RAS
