 
Summary: Ab initio simulation of charged slabs at constant chemical potential
A. Y. Lozovoi
Atomistic Simulation Group, School of Mathematics and Physics, The Queen's University of Belfast,
Belfast BT7 1NN, Northern Ireland, United Kingdom and University of Cambridge, Chemistry Department,
Lensfield Road, Cambridge CB2 1EW, United Kingdom
A. Alavi
University of Cambridge, Chemistry Department, Lensfield Road, Cambridge CB2 1EW, United Kingdom
J. Kohanoff and R. M. LyndenBell
Atomistic Simulation Group, School of Mathematics and Physics, The Queen's University of Belfast,
Belfast BT7 1NN, Northern Ireland, United Kingdom
Received 29 March 2001; accepted 25 April 2001
We present a practical scheme for performing ab initio supercell calculations of charged slabs at
constant electron chemical potential , rather than at constant number of electrons Ne . To this end,
we define the chemical potential relative to a plane or ``reference electrode'' at a finite distance
from the slab the distance should reflect the particular geometry of the situation being modeled . To
avoid a net charge in the supercell, and thus make possible a standard supercell calculation, we
restore the electroneutrality of the periodically repeated unit by means of a compensating charge,
whose contribution to the total energy and potential is subtracted afterwards. The ``constant ''
mode enables one to perform supercell calculation on slabs, where the slab is kept at a fixed
potential relative to the reference electrode. We expect this to be useful in modeling many
