Hi Sophia, I am by no means an expert, but I would try increasing the Mesh Cutoff. I usually use 300 Ry, but your system is quite large. Try 150 Ry and see what happens.
Cheers, Marty On Tue, Apr 1, 2008 at 9:19 AM, Sophia Nishad <[EMAIL PROTECTED]> wrote: > Thanks a lot for outstanding support and help from the group. > > > On Sun, Mar 30, 2008 at 10:22 PM, Sophia Nishad <[EMAIL PROTECTED]> > wrote: > > > Hi, > > > > I am a new user of SIESTA. I have been trying to reproduce the results > > for Si as mention in Soler et. al 2002 paper, before I go for my actual > > calculations. > > > > I have used the DZP Basis mentioned at > > http://www.uam.es/departamentos/ciencias/fismateriac/siesta/ > > Pseudopotential at > > http://www.uam.es/departamentos/ciencias/fismateriac/siesta/ > > > > My calculation for 64-atoms: > > 1) Lattice Constant: I changed the lattice parameter and find the energy > > and plotting that I find 5.45 Ang, instead of 5.40 as reported in the > > paper. Why this so different? > > > > 2) Bulk modulus: With B = V*Curvature = V*2c3 = 15 MPa, which is far > > less than 98.6 MPa? Why? Here, c3 is defined as E =C1 + c2*V + c3*V^2, > > curve fit to the E vs V curve. > > > > 3) Cohesive Energy: I find energy per atom 107.759eV in the bulk. Now to > > calculate energy per atom I tried to use the suggestions given at > > http://www.mail-archive.com/siesta-l@listserv.uam.es/msg03118.html > > I get -7.49eV/atom as pseudopotential calculation, and -576.38eV/atom as > > ae. So, which one is the energy of the free atom. None is a good one for > > comparing with the energy I got from bulk to find the cohesive energy. > > > > I really tried to search the archive and find solutions to these. I > > could not find any explicit answers. I am not sure what I am missing. *Some > > expert's simple directions can solve the problem right away*. I really > > need this help. > > > > > > Thanks in advance, > > Sophia > > Univ. of California - Berkeley > > > > Attached fdf file > > > > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ > > > > # > > ----------------------------------------------------------------------------- > > # FDF for a cubic c-Si supercell with 64 atoms > > # > > # E. Artacho, April 1999 > > # > > ----------------------------------------------------------------------------- > > > > SystemName 64-atom Si > > SystemLabel Si > > > > NumberOfAtoms 64 > > NumberOfSpecies 1 > > > > %block ChemicalSpeciesLabel > > 1 14 Si > > %endblock ChemicalSpeciesLabel > > > > PAO.BasisSize DZP > > PAO.EnergyShift 20 meV > > > > %Block PAO.Basis > > Si 3 -0.46385 > > n=3 0 2 E 15.42551 4.96988 > > 7.00000 4.37722 > > 1.00000 1.00000 > > n=3 1 2 E 4.69636 3.83128 > > 7.00000 4.09123 > > 1.00000 1.00000 > > n=3 2 1 E 11.96912 0.03131 > > 4.55426 > > 1.00000 > > %EndBlock PAO.Basis > > > > > > LatticeConstant 5.430 Ang > > %block LatticeVectors > > 2.000 0.000 0.000 > > 0.000 2.000 0.000 > > 0.000 0.000 2.000 > > %endblock LatticeVectors > > > > %block kgrid_Monkhorst_Pack > > 2 0 0 0.0 > > 0 2 0 0.0 > > 0 0 2 0.0 > > %endblock kgrid_Monkhorst_Pack > > > > > > MeshCutoff 40.0 Ry > > > > MaxSCFIterations 100 > > DM.MixingWeight 0.3 > > DM.NumberPulay 3 > > DM.Tolerance 1.d-3 > > DM.UseSaveDM > > XC.functional LDA > > XC.authors CA > > > > > > SolutionMethod diagon > > ElectronicTemperature 25 meV > > > > WriteForces true > > WriteCoorStep true > > > > MD.TypeOfRun cg > > MD.NumCGsteps 0 > > MD.MaxCGDispl 0.1 Ang > > MD.MaxForceTol 0.01 eV/Ang # earler 0.04 > > SaveRho true > > > > AtomicCoordinatesFormat ScaledCartesian > > %block AtomicCoordinatesAndAtomicSpecies > > 0.00000 0.00000 0.00000 1 > > 0.00000 0.50000 0.50000 1 > > 0.25000 0.25000 0.75000 1 > > 0.25000 0.75000 0.25000 1 > > 0.50000 0.00000 0.50000 1 > > 0.50000 0.50000 0.00000 1 > > 0.75000 0.25000 0.25000 1 > > 0.75000 0.75000 0.75000 1 > > 0.00000 0.00000 1.00000 1 > > 0.00000 0.50000 1.50000 1 > > 0.25000 0.25000 1.75000 1 > > 0.25000 0.75000 1.25000 1 > > 0.50000 0.00000 1.50000 1 > > 0.50000 0.50000 1.00000 1 > > 0.75000 0.25000 1.25000 1 > > 0.75000 0.75000 1.75000 1 > > 0.00000 1.00000 0.00000 1 > > 0.00000 1.50000 0.50000 1 > > 0.25000 1.25000 0.75000 1 > > 0.25000 1.75000 0.25000 1 > > 0.50000 1.00000 0.50000 1 > > 0.50000 1.50000 0.00000 1 > > 0.75000 1.25000 0.25000 1 > > 0.75000 1.75000 0.75000 1 > > 0.00000 1.00000 1.00000 1 > > 0.00000 1.50000 1.50000 1 > > 0.25000 1.25000 1.75000 1 > > 0.25000 1.75000 1.25000 1 > > 0.50000 1.00000 1.50000 1 > > 0.50000 1.50000 1.00000 1 > > 0.75000 1.25000 1.25000 1 > > 0.75000 1.75000 1.75000 1 > > 1.00000 0.00000 0.00000 1 > > 1.00000 0.50000 0.50000 1 > > 1.25000 0.25000 0.75000 1 > > 1.25000 0.75000 0.25000 1 > > 1.50000 0.00000 0.50000 1 > > 1.50000 0.50000 0.00000 1 > > 1.75000 0.25000 0.25000 1 > > 1.75000 0.75000 0.75000 1 > > 1.00000 0.00000 1.00000 1 > > 1.00000 0.50000 1.50000 1 > > 1.25000 0.25000 1.75000 1 > > 1.25000 0.75000 1.25000 1 > > 1.50000 0.00000 1.50000 1 > > 1.50000 0.50000 1.00000 1 > > 1.75000 0.25000 1.25000 1 > > 1.75000 0.75000 1.75000 1 > > 1.00000 1.00000 0.00000 1 > > 1.00000 1.50000 0.50000 1 > > 1.25000 1.25000 0.75000 1 > > 1.25000 1.75000 0.25000 1 > > 1.50000 1.00000 0.50000 1 > > 1.50000 1.50000 0.00000 1 > > 1.75000 1.25000 0.25000 1 > > 1.75000 1.75000 0.75000 1 > > 1.00000 1.00000 1.00000 1 > > 1.00000 1.50000 1.50000 1 > > 1.25000 1.25000 1.75000 1 > > 1.25000 1.75000 1.25000 1 > > 1.50000 1.00000 1.50000 1 > > 1.50000 1.50000 1.00000 1 > > 1.75000 1.25000 1.25000 1 > > 1.75000 1.75000 1.75000 1 > > %endblock AtomicCoordinatesAndAtomicSpecies > > > >
