Dear All: I´m doing my first relaxation with SIESTA and I´ve some problems. I want to do a simultaneous relaxation of the atomic coordinates and the lattice parameters of portlandite Ca(OH)2. My problem is that the lattice parameters decrease alarming, reducing the volume in almost the 30%. I think the problem is in MD.PreconditionVariableCell paramenter, becouse I don´t undestand really what does it mean, but I´m not sure. I hope somebody help me, thank you.
The input is like this: SystemName portlandita SystemLabel P NumberOfAtoms 5 NumberOfSpecies 3 %block ChemicalSpeciesLabel 1 8 O l 2 1 H 3 20 CA %endblock ChemicalSpeciesLabel %block PAO.Basis Ca 5 1.90213 n=3 0 1 E 61.56667 4.61281 5.29940 1.00000 n=4 0 2 E 164.86383 5.38785 6.76569 4.96452 1.00000 1.00000 n=3 1 1 E 86.94959 3.48034 6.32716 1.00000 n=4 1 1 E 112.03339 4.98424 7.49434 1.00000 n=3 2 1 E 87.65847 5.83989 6.49046 1.00000 H 2 2.72022 n=1 0 2 E 134.23176 5.88089 6.41415 3.59161 1.00000 1.00000 n=2 1 1 E 132.57601 5.96051 6.73959 1.00000 O 3 -0.2062 n=2 0 2 E 89.2503 5.0971 5.96175037505551 2.52330170654204 1.00000000000000 1.00000000000000 n=2 1 2 E 76.3408 7.1750 1.00000000000000 1.00000000000000 n=2 2 1 E 104.3073 0.0000 3.92324958680187 1.00000000000000 %endblock PAO.Basis MD.TypeOfRun CG MD.VariableCell .true. MD.NumCGSteps 100 MD.PreconditionVariableCell 5 Ang MD.MaxStressTol 1.0 GPa MD.TargetPressure 0.0 GPa %block MD.TargetStress -1.0, -1.0, -1.0, 0, 0, 0 %endblock MDTargetStress DM.NumberPulay 5 DM.NumberKick 4 xc.functional GGA xc.authors PBE SpinPolarized .true. MeshCutoff 150.0000000 Ry OccupationFunction FD ElectronicTemperature 580 K %block kgrid_Monkhorst_pack 6 0 0 0. 0 6 0 0. 0 0 6 0. %endblock kgrid_Monkhorst_pack LatticeConstant 1.0 Ang %block LatticeParameters 3.5925 3.5925 4.905 90 90 120 %endblock LatticeParameters AtomicCoordinatesFormat Fractional %block AtomicCoordinatesAndAtomicSpecies 0.000000 0.000000 0.000000 3 0.333333 0.666667 0.233000 2 0.666667 0.333333 0.767000 2 0.333333 0.666667 0.418000 1 0.666667 0.333333 0.582000 1 %endblock AtomicCoordinatesAndAtomicSpecies AtomCoorFormatOut ScaledCartesian END --------------------------------------------------------------------------------------------------------------------------------------------------------------------- Este mensaje se dirige exclusivamente a su destinatario y puede contener información privilegiada o confidencial. Si no es vd. el destinatario indicado, queda notificado de que la utilización, divulgación y/o copia sin autorización está prohibida en virtud de la legislación vigente. Si ha recibido este mensaje por error, le rogamos que nos lo comunique inmediatamente por esta misma vía y proceda a su destrucción. Mezu honek eta erantsita dituen agiriek (baldin baditu) isilpeko informazioa izan dezakete. Hori dela eta, hutsegite baten ondorioz jasotzen duenak jakin beza bertan dagoen informazioa ezkutukoa dela eta legeak galarazi egiten duela berori baimenik gabe erabiltzea. This message is intended exclusively for its addressee and may contain information that is CONFIDENTIAL and protected by professional privilege. If you are not the intended recipient you are hereby notified that any dissemination, copy or disclosure of this communication is strictly prohibited by law. If this message has been received in error, please immediately notify us via e-mail and delete it. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------