Suman, could you give us a more precise idea of how the band structure, lattice parameters and cohesive energy compare with the data in the literature (that is, providing numbers and an illustration of the band structure)?
With the very scarce information you provide I can only think of trivial mistakes, such as not placing the correct coordinates of k-points in the BZ of the beta Sn phase, or incorrect coordinates for this same phase. Check for that. Marcos On Wed, Jan 19, 2011 at 3:38 PM, suman kalyan sahoo <kalyan_...@yahoo.co.in>wrote: > > > --- On *Wed, 19/1/11, suman kalyan sahoo <kalyan_...@yahoo.co.in>* wrote: > > > From: suman kalyan sahoo <kalyan_...@yahoo.co.in> > Subject: mismatch in band structure of bulk tin in beta and alpha phase. > To: siesta-l@uam.es > Date: Wednesday, 19 January, 2011, 12:17 AM > > Dear users > > I am doing calculation on bulk beta-Sn (tin),as well as alpha tin. > I am taking the the > pseudo potential given in siesta home website > first few lines are > Sn pb nrl nc > ATM 3.2.2 9-APR-07 Troullier-Martins > 5s 2.00 r= 2.43/5p 2.00 r= 2.49/5d 0.00 r= 2.82/4f 0.00 r= 2.82/ > 4 0 1176 4.957504353333E-05 1.250000000000E-02 4.000000000000 > > Radial grid follows > 6.235772827088E-07 1.254998202050E-06 1.894361418827E-06 > 2.541766834843E-06 > 3.197315608511E-06 3.861110170662E-06 4.533254240545E-06 > 5.213852842040E-06 > 5.903012320063E-06 6.600840357183E-06 7.307445990452E-06 > 8.022939628438E-06 > > and basis set for Sn as follows > %block PAO.Basis > Sn 2 > n= 5 0 2 > 6.030 4.773 > n= 5 1 2 P 1 > 7.675 > 5.615 > %endblock PAO.Basis > as well as > %block PAO.Basis # Define Basis set > > Sn 3 # Species label, number of l-shells > n=5 0 2 P 1 # n, l, Nzeta, Polarization, NzetaPol > > 5.830 4.597 > 1.000 1.000 > n=5 1 2 # n, l, Nzeta > 7.675 5.545 > 1.000 1.000 > n=4 2 1 # n, l, Nzeta > 3.449 > 1.000 > > %endblock PAO.Basis > > With this potential and both basis set the parameters (Lattice > constant,cohesive energy and band structure)for tin in diamond form > is well reproduce with the previous literature. But when i draw the band > structure for bct ( beta Sn) phase , the band structure is not match at all > with the literature data. where as cohesive energy and lattice constant is > close to the experimental value. > > So please any one give me > an idea that with same basis set and pseudopotential file both phases of > (alpha and beta )tin are not reproducible ? > What basis set and pseudopotential is suitable to calculate the beta phase of > Sn ? > > Kindly suggest me what to do ? > > With best > regards > Suman K Sahoo > Ph.D Student > Deptt. of Chemistry > Visva Bharati, Santiniketan > India > > > > > > > >
