Dear all,

I tried to compute the polarization for tetragonal and cubic BaTiO3. I was
surprised to see very little difference between the computed values as
under. Please advise me if anybody knows about that. I expected the
polarization to be zero or small for cubic.



tetragonal batio3:

siesta: Macroscopic polarization per unit cell (a.u.):
siesta: Along the lattice vectors     75.400102   75.400102   76.154103
siesta: Along cartesian directions    75.400102   75.400102   76.154103

siesta: Macroscopic polarization per unit cell (Debye):
siesta: Along the lattice vectors    191.648076  191.648075  193.564556
siesta: Along cartesian directions   191.648076  191.648075  193.564556


cubic batio3:

siesta: Macroscopic polarization per unit cell (a.u.):
siesta: Along the lattice vectors     75.400102   75.400102   75.400102
siesta: Along cartesian directions    75.400102   75.400102   75.400102

siesta: Macroscopic polarization per unit cell (Debye):
siesta: Along the lattice vectors    191.648075  191.648075  191.648075
siesta: Along cartesian directions   191.648075  191.648075  191.648075


thanks,

Ghous



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