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Silicon cd force calculations Date: 2012/08/28 20:21 Name: Dariusz Chrobak   <dariusz.chrobak@gmail.com> Dear All, I encountered a small problem that concerns force calculations. My structure is a simple cubic diamond Si: ************************************************************ DATA.PATH /home/nhl/opt/openmx3.6/DFT_DATA11 System.Name d level.of.stdout 1 level.of.fileout 3 Species.Number 1 <Definition.of.Atomic.Species Si Si7.0-s2p2d1 Si_CA11 Definition.of.Atomic.Species> Atoms.Number 8 Atoms.SpeciesAndCoordinates.Unit FRAC <Atoms.SpeciesAndCoordinates 1 Si -0.50 -0.50 -0.50 2 2 2 Si 0.0 0.0 -0.50 2 2 3 Si 0.0 -0.50 0.0 2 2 4 Si -0.50 0.0 0.0 2 2 5 Si -0.25 -0.25 -0.25 2 2 6 Si 0.25 0.25 -0.25 2 2 7 Si 0.25 -0.25 0.25 2 2 8 Si -0.25 0.25 0.25 2 2 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit AU <Atoms.UnitVectors 10.2612 0.0 0.0 0.0 10.2612 0.0 0.0 0.0 10.2612 Atoms.UnitVectors> scf.restart off scf.XcType LDA scf.SpinPolarization off scf.ElectronicTemperature 300.0 scf.energycutoff 160.0 scf.maxIter 100 scf.EigenvalueSolver band scf.lapack.dste dstevx scf.Kgrid 8 8 8 scf.Mixing.Type rmm-diisk scf.Init.Mixing.Weight 0.010 scf.Min.Mixing.Weight 0.001 scf.Max.Mixing.Weight 0.200 scf.Mixing.History 15 scf.Mixing.StartPulay 5 scf.criterion 1.0e-7 orderN.HoppingRanges 6.0 orderN.NumHoppings 1 ************************************************************ In the output file I found the following table of atomic forces: ************************************************************ <coordinates.forces 8 1 Si 2.71500 2.71500 2.71500 -0.000004654408 0.000000000007 -0.000000000004 2 Si 0.00000 0.00000 2.71500 -0.000004654413 0.000000000008 -0.000000000013 3 Si 0.00000 2.71500 0.00000 -0.000004654408 0.000000000014 -0.000000000006 4 Si 2.71500 0.00000 0.00000 -0.000004654419 0.000000000011 -0.000000000005 5 Si 4.07250 4.07250 4.07250 -0.000004654400 -0.000000000011 0.000000000003 6 Si 1.35750 1.35750 4.07250 -0.000004654397 -0.000000000005 0.000000000010 7 Si 1.35750 4.07250 1.35750 -0.000004654406 -0.000000000010 0.000000000007 8 Si 4.07250 1.35750 1.35750 -0.000004654401 -0.000000000014 0.000000000009 coordinates.forces> ************************************************************ They are asymetric so the question is siply why? Thank you in advance for any comment. BR, Darek

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Re: Silicon cd force calculations ( No.1 ) Date: 2012/08/29 09:10 Name: T. Ozaki Hi, Thank you for your report. We have also noticed it and identified that this comes from the calculation of force(8) in Total_Energy.c. In fact, the numerical integration involved causes the slight asymmetric force. The problem will be fixed in the next release. Thank you. Regards, TO Re: Silicon cd force calculations ( No.2 ) Date: 2012/08/29 18:34 Name: Dariusz Chrobak  <dariusz.chrobak@gmail.com> Hi, Thank you for comment. I hope that this disfunctionality does not affect other important feautures of the openmx great software. This is difficult to trace all relationships between parts of code for persons who are not developers. Best regards, Darek

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