Dear Dan, I have noticed similar problems. Mulliken charges depend on the atomic basis set used. In Siesta the cutoff radius (of H) seems to be the critical parameter. I suggest that you check the dipol moment of an isolated water molecule (10 Angstrom box). It should have the correct magnitude and sign for the basis set settings you use.
Regards, Ulrich. From: Dan Gil <[email protected]> To: <[email protected]> Sent: 06.10.2017 16:13 Subject: [SIESTA-L] Mulliken Charges on Water Hi, I am using Siesta 3.2 and ran into a strange problem. I simulate a water molecule and the Mulliken charges are wrong. It shows that the oxygen atom is positively charged and the two hydrogens are negatively charged. The Hirshfeld and Voronoi populations are fine. Did I run into a bug? input.fdf NumberOfAtoms 3 NumberOfSpecies 4 %block ChemicalSpeciesLabel 1 13 Al 2 14 Si 3 8 O 4 1 H %endblock ChemicalSpeciesLabel PAO.BasisType nodes %block PAO.BasisSizes Al DZP Si DZP O DZP H DZP %endblock PAO.BasisSizes XC.functional GGA XC.authors PBE # SCF options MaxSCFIterations 200 DM.MixingWeight 0.25 # New DM amount for next SCF cycle DM.Tolerance 1.d-6 # Tolerance in maximum difference SolutionMethod diagon # OrderN or Diagon MeshCutoff 400 Ry DM.Require.Energy.Convergence .true. DM.Energy.Tolerance 1.d-6 eV MD.TypeOfRun CG MD.NumCGsteps 100 MD.InitialTemperature 300.0 K MD.TargetTemperature 300.0 K WriteHirshfeldPop .true. WriteVoronoiPop .true. WriteMullikenPop 1 LatticeConstant 1 Ang %block LatticeVectors 9.5160000000 0.0000000000 0.0000000000 -4.7580000000 8.2411000000 0.0000000000 0.0000000000 0.0000000000 48.2792733630 %endblock LatticeVectors WarningMinimumAtiomicDistance 1.0 Ang AtomicCoordinatesFormat NotScaledCartesianAng %block AtomicCoordinatesAndAtomicSpecies < Coord.fdf Coord.fdf 5.265981 -1.943725 -6.378528 3 4.222545 -1.943725 -6.378528 4 5.612381 -0.997652 -6.378528 4 Output (excerpts) mulliken: Mulliken Atomic and Orbital Populations: Species: O Atom Qatom Qorb 2s 2s 2py 2pz 2px 2py 2pz 2px 2Pdxy 2Pdyz 2Pdz2 2Pdxz 2Pdx2-y2 1 5.764 1.436 -0.027 1.363 1.793 1.235 -0.023 -0.003 -0.034 0.003 0.002 0.005 0.001 0.014 Species: H Atom Qatom Qorb 1s 1s 1Ppy 1Ppz 1Ppx 2 1.118 0.845 0.036 0.063 0.104 0.070 3 1.118 0.845 0.036 0.091 0.104 0.042 Hirshfeld Net Atomic Populations: Atom # Qatom Species 1 -0.234 O 2 0.117 H 3 0.117 H Voronoi Net Atomic Populations: Atom # Qatom Species 1 -0.171 O 2 0.086 H 3 0.085 H Best Regards, Dan ------------------------------------------------- Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 1 D-40237 Düsseldorf Handelsregister B 2533 Amtsgericht Düsseldorf Geschäftsführung Prof. Dr. Gerhard Dehm Prof. Dr. Jörg Neugebauer Prof. Dr. Dierk Raabe Dr. Kai de Weldige Ust.-Id.-Nr.: DE 11 93 58 514 Steuernummer: 105 5891 1000 Please consider that invitations and e-mails of our institute are only valid if they end with …@mpie.de. If you are not sure of the validity please contact [email protected] Bitte beachten Sie, dass Einladungen zu Veranstaltungen und E-Mails aus unserem Haus nur mit der Endung …@mpie.de gültig sind. In Zweifelsfällen wenden Sie sich bitte an [email protected] -------------------------------------------------
