Thanks for your tips.But could you tell me how to get the diffuse basis? Need I to just adjust my present TZP basis,or find a new basis.I have no idea about this problem.
2011/7/1 Herbert Fruchtl <[email protected]> > For weak interactions like this, you need to use a diffuse basis and to > correct for BSSE. The latter is not trivial if you want to optimise the > geometry. > > Herbert > > > On 07/01/2011 08:02 AM, Robin H wrote: > >> Dear siesta users,I'm now puzzled with the results by siesta in >> calculating the >> interaction energy of benzene and molecule hydrogen.According to a >> reference(Fabien Tran et al,J. Phys. Chem. B 2002, 106, 8689-8696),they >> used the >> Gaussian packages,and got the results much agreed with the experiment >> datas:when >> the orientation of the H2 axis is parallel to X axis ,the interation >> energy is >> 0.42 kcal/mol,and when the orientation is parallel to Z axis,the >> interaction >> energy is 0.72 kcal/mol.But I tried with siesta (the parameters has been >> kept >> the same as possible as I can ),the former results is 3.7997kcal/mol,and >> the >> latter is becoming to 4.252kcal/mol.Both of the calculation has a big >> difference >> after I checked all the possible reasons.I could't understand why siesta >> can't >> make an accurate results.So I want to know is there any possible reason >> about >> the precision of siesta? >> *the following is an input file of two examples:* >> SystemName Ben+h2_z >> SystemLabel ben+h2_z >> NumberOfAtoms 14 >> NumberOfSpecies 2 >> %block ChemicalSpeciesLabel >> 1 6 C >> 2 1 H >> %endblock ChemicalSpeciesLabel >> #%block PAO.BasisSizes >> # O DZP >> # Zn DZP >> # C DZP >> # H DZP >> #%endblock PAO.BasisSizes >> %block PAO.Basis >> C 2 >> n=2 0 3 >> 4.088 3.347 3.002 >> 1.000 1.000 1.000 >> n=2 1 3 P 1 >> 4.870 3.347 3.002 >> 1.000 1.000 1.000 >> H 1 >> n=1 0 3 P 1 >> 4.593 3.713 3.002 >> 1.000 1.000 1.000 >> %endblock PAO.Basis >> #PAO.BasisSize DZP >> PAO.EnergyShift 100 meV >> PAO.BasisType split >> LatticeConstant 15.000 Ang >> #%block LatticeParameters >> # 2.460 2.460 6.800 90.000 90.000 120.000 >> #%endblock LatticeParameters >> %block LatticeVectors >> 1.000 0.000 0.000 >> 0.000 1.000 0.000 >> 0.000 0.000 1.000 >> %endblock LatticeVectors >> >> #Kgrid_cutoff 5.00000 Ang >> %block kgrid_Monkhorst_Pack >> 1 0 0 0.0 >> 0 1 0 0.0 >> 0 0 1 0.0 >> %endblock kgrid_Monkhorst_Pack >> # %block BandLines >> # 1 0.000 0.000 -1.000 >> # 100 0.000 0.000 1.000 >> # %endblock BandLines >> #%block GeometryConstraints >> # position from 1 to 424 >> #%endblock GeometryConstraints >> >> #SPIN options >> XC.functional GGA >> XC.authors PBE >> NetCharge 0 >> SpinPolarized F >> FixSpin F >> TotalSpin 0.0 >> MeshCutoff 300.0 Ry >> FilterCutoff 100. Ry >> # SCF options >> #%block DM.InitSpin >> #%endblock DM.InitSpin >> MaxSCFIterations 100 # Maximum number of SCF iter >> DM.MixingWeight 0.10 # New DM amount for next SCF cycle >> DM.NumberPulay 10 >> DM.Tolerance 1.d-4 # Tolerance in maximum difference between input and >> output DM >> DM.UseSaveDM T # to use continuation files >> DM.MixSCF1 F >> DM.PulayOnFile F # Store in memory ('F') or in files ('T') >> SolutionMethod diagon # OrderN or Diagon >> ElectronicTemperature 100.0 K #Temp. for Fermi smearing >> >> # MD options >> >> MD.TypeOfRun cg >> MD.NumCGsteps 150 >> MD.MaxCGDispl 0.1 Ang >> MD.MaxForceTol 0.01 eV/Ang >> MD.VariableCell F >> MD.MaxStressTol 0.05 GPa >> #MD.TypeOfRun fc >> #MD.FCDispl 0.04 Ang >> #MD.FCfirst 1 >> #MD.FClast 200 >> AtomicCoordinatesFormat Ang >> %block AtomicCoordinatesAndAtomicSpec**ies < ben+h2_z.xyz >> %endblock AtomicCoordinatesAndAtomicSpec**ies >> # OUTPUT options >> WriteCoorInitial T >> WriteCoorStep T >> WriteCoorXmol T >> WriteForces T >> WriteEigenvalues T # If .false., it writes them in the file >> Systemlabel.EIG >> WriteMullikenPop 1 # Write Mulliken Population Analysis >> #WriteKpoints T >> #WriteKbands T >> #WriteBands T >> WriteMDCoorXmol F >> WriteMDhistory F >> # options for saving or reading information >> MD.UseSaveZM F # Use stored positions and velocities >> MD.UseSaveCG F # Use stored positions and velocities >> SaveRho T # Write valence pseudocharge at the mesh >> #SaveDeltaRho T # Write RHOscf-RHOatm at the mesh >> #SaveElectrostaticPotential T # Write the total elect. pot. at the mesh >> # (local pseudopotential + Hartree) >> SaveHS T >> SaveTotalPotential T # write the valence total effective local potential >> # (local pseudopotential + Hartree + Vxc) >> #WriteSiestaDim T # Write minimum dim to siesta.h and stop >> #WriteDenchar T # Write information for DENCHAR >> >> > -- > Herbert Fruchtl > Senior Scientific Computing Officer > School of Chemistry, School of Mathematics and Statistics > University of St Andrews > -- > The University of St Andrews is a charity registered in Scotland: > No SC013532 >
