Please... help.. me

[jjkim]

I'm not a expert in this part
so very confuse.. to understand to use the VASP CODE.


I try to extend the 4 atom basis fcc primitive cell to 2x2x2 and 3x3x3 lattice unit.. (32 and 108 lattice site per unit cell)


Is it right the 32 and 108 means the atoms number in the cell?

if it is right
Should I put the 32 or 108 coordinates in the POSCAR files?

if it is wrong
how many atoms exist in the cell for each case?

please help me...

[panda]

Remember that a lattice site and an atomic site are not the same thing - you can have more than one atom occupying a lattice site although if you only have one atom occupying each lattice site then the number of atoms and the number of lattice sites will be equal. Because each primitive cell contains one atom per lattice site in this simple case you are correct, however please keep in mind that for more complicated space groups you may have a cluster of atoms on each lattice site, in which case the number of atoms and lattice sites would be different.