I want to add a charged vacancy in my quantum espresso pw.x input file
Dear Khaled A. Abdelghafar,
I admittedly do not understand what you want to do. A vacancy means that you remove a particular atom from your structure. You cannot remove an atom and leave somewhat an extra charge behind.
I assume that somewhat you want to charge the defected system. What you can do with QE is
1) Remove your atom — delete its entry in the Atomic_POSITIONS and decrease nat by 1
2) Include in the SYSTEM section the flag tot_charge — +1 means an electron missing, -1 one extra electron. Notice, however, that in a periodic system this includes an extra background to make the unit cell neutral.
I wish to point out that a vacancy might in some case act as a dopant since the electrons that are not forming any bond might form an extra level or move to the conduction band.
I hope this helps,
Roberto
Roberto D'Agosta I have read that i should add ghost atom to model and simulate charged point defect
remove the desired atom in the input file to make a neutral vacancy and in the SYSTEM flag write tot_charge=+1 or -1 accordingly for positive or negative charge. If your vacancy is ++ charged, write tot_charge=+2!
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