This example can of course be compared directly to the Cu slab. This example is important, as SCF convergence is frequently difficult in slab calculations. The specifications in the
DIIS blocks are typical. Such settings are recommended in slab calculations with convergence problems.
DEGENERATE subkey specifies that bands with the same energy should have the same occupation numbers. This helps SCF convergence. The same is true for the values for the
MIXING subkey in the SCF block and the
DIMIX subkey in the
DIIS block. Please note that the recommended value for
Mixing is approximately half of the value for
Another important feature in BAND is that it enables relativistic treatments for heavy nuclei. Both the
ZORA scalar relativistic option and spin-orbit effects have been implemented. The line
Relativistic ZORA SPIN
specifies that in this case both the scalar relativistic effects (ZORA) and spin-orbit effects (SPIN) will be taken into account. Whereas the
ZORA keyword does not make the calculation much more time-consuming, the same cannot be said for the spin-orbit option. Usually the ZORA keyword will give the most pronounced relativistic effects and the spin-orbit effects will be a fairly minor correction to that. We therefore recommend scalar ZORA as a good default method for treating heavy nuclei.
DEPENDENCY keyword means that the calculation should continue even if the basis is nearly linearly dependent (as measured by the eigenvalues of the overlap matrix).
$ADFBIN/band << eor DefaultsConvention pre2014 Title Platinum slab Comment Technical Low quadratic K space integration Low real space integration accuracy Features Lattice : 2D Unit cell : 3 atoms, 1x1 Basis : NO+STO w/ core Options : Spinorbit ZORA End Convergence Degenerate 1.0E-03 End SCF Iterations 60 Mixing 0.06 End DIIS NCycleDamp 15 DiMix 0.15 End KSpace 3 Accuracy 3 Relativistic ZORA SPIN Dependency Basis=1E-8 Define latt=7.41 lvec=latt/SQRT(2.0) ysh=lvec/SQRT(3.0) dlay=latt/SQRT(3.0) End Lattice SQRT(3.0)*lvec/2.0 0.5*lvec SQRT(3.0)*lvec/2.0 -0.5*lvec End Atoms Pt Pt 0 0 0 :: layer 1 Pt -ysh 0.0 -dlay :: layer 2 Pt ysh 0.0 -2.0*dlay :: layer 3 End END INPUT eor