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
