Thanks Emilio. That makes sense.
On 12/8/09, Emilio Artacho <[email protected]> wrote: > > Hi Ben > > You may be referring to something else, > sorry if I misunderstand you. The virial > relation you refer to is the one holding > for particles interacting via 1/r potentials, > which is not the case here: cores interact > with valence electrons via pseudopotentials. > In an all-electron calculation you should recover the virial result, since > there you > do have electrons and nuclei, all seeing > each other by 1/r. > (A minor point there: even for all electron, if you work with a finite > basis like our LCAO, the virial result is only recovered in the converged > basis limit, unless you scale your basis functions and minimise the energy > w.r.t > the scaling factors). > > Emilio > > > On Dec 8 2009, Ben Martin wrote: > > I'm having trouble resolving the energy output in SIESTA, specifically >> that it seems to violate the virial theorem. The virial theorem requires >> that the EXACT solution must satisfy kinetic energy = - total energy, but >> I'm not getting anywhere close to that. Below is the energy output of an >> optimization I ran: >> >> Final energy (eV): >> Kinetic = 5497.928558 >> Hartree = 2350.057707 >> Ext. field = 0.000000 >> Exch.-corr. = -1786.932583 >> Ion-electron = -9917.735789 >> Ion-ion = -3791.753153 >> Ekinion = 0.000000 >> Total = -7648.435261 >> >> The relaxation runs fine and the relaxed coordinates are good, but as you >> can see there is a discrepency of ~2000 eV (or about 30%) between Kinetic >> and -Total. >> >> Am I missing something? >> >> Thanks, >> Ben >> >> ************************************* >> #General system specifications >> SystemName Olivine >> SystemLabel Ol >> NumberOfAtoms 28 >> NumberOfSpecies 3 >> >> %block ChemicalSpeciesLabel >> 1 12 Mg # Species index, atomic number, species label >> 2 14 Si # Species index, atomic number, species label >> 3 8 O # Species index, atomic number, species label >> %endblock ChemicalSpeciesLabel >> >> AtomicCoordinatesFormat Ang >> >> %block LatticeVectors >> 4.6300 0.00000 0.00000 >> 0.0000 9.96000 0.00000 >> 0.0000 0.00000 5.98000 >> %endblock LatticeVectors >> >> %block AtomicCoordinatesAndAtomicSpecies >> 28 atom coordinates, etc. >> %endblock AtomicCoordinatesAndAtomicSpecies >> >> %block GeometryConstraints >> position 1 >> %endblock GeometryConstraints >> >> %block PAO.Basis >> bases from the SIESTA database >> %endblock PAO.Basis >> >> XC.Functional LDA >> XC.Authors CA >> >> MeshCutoff 300.0 Ry >> MaxSCFIterations 600 >> DM.MixingWeight 0.01 >> MD.TypeOfRun CG >> MD.NumCGSteps 600 >> MD.VariableCell >> >> SolutionMethod diagon >> AtomCoorFormatOut Ang >> >> MD.MaxForceTol 0.004 ev/Ang >> DM.Tolerance 1.d-4 >> DM.EnergyTolerance 1.d-4 ev >> MD.MaxCGDispl 0.000635 Ang >> >> WriteForces .true. >> >> > -- > Emilio Artacho > > Department of Earth Sciences, University of Cambridge > Downing Street, Cambridge CB2 3EQ, UK > Tel. (+44/0) 1223 333480, Fax (+44/0) 1223 333450 > [email protected], > http://www.esc.cam.ac.uk/~emilio<http://www.esc.cam.ac.uk/%7Eemilio> > > >
