# Crystalline aluminum : computation of the total energy
#
# Determination of the surface energy of aluminum :
# convergence with respect to the number of vacuum layers.

ndtset 2

#Definition of the unit cell
acell  3*7.50559090E+00  # Lattice parameters of bulk aluminum
rprim1 0.5 -0.5  0.0     
       0.5  0.5  0.0    
       0.0  0.0  2.5    
rprim2 0.5 -0.5  0.0    
       0.5  0.5  0.0    
       0.0  0.0  3.0    


#Definition of occupation numbers
occopt 4
tsmear 0.04

#Definition of the k-point grid 
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetry
ngkpt  4 4 1  
nshiftk 2
shiftk  0.5 0.0 0.0
        0.0 0.5 0.0

#Definition of the atom types
ntypat 1          # There is only one type of atom
znucl 13          # The keyword "znucl" refers to the atomic number of the 
                  # possible type(s) of atom. The pseudopotential(s) 
                  # mentioned in the "files" file must correspond
                  # to the type(s) of atom. Here, the only type is Aluminum
                         

#Definition of the atoms
natom 3           # Three atoms per cell: three aluminum layers and some vacuum
typat 3*1         # These atoms are of type 1, that is, Aluminum
xcart             
   3*0.0             # Triplet giving the CARTESIAN coordinates of atom 1.
   0.0  2*3.75279545 # Triplet giving the CARTESIAN coordinates of atom 2.
   2*0.0  7.5055909  # Triplet giving the CARTESIAN coordinates of atom 3.
 
#The relaxation
ionmov 3
tolmxf 5.0d-4
ntime 10

#Exchange-correlation functional
ixc 1             # LDA Teter Pade parametrization

#Definition of the planewave basis set
ecut  6.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 10          # Maximal number of SCF cycles
toldff 5.0d-5