adesh.zip
:Click HERE to Download a DEMO version of ADESH
(a) Figure 1 shows the atomistic configuration
of a 109.5 degree tilt grain boundary. Blue circles represent
oxygen atoms and green circles show positions of Nickel atoms.
Across the grain boundary plane, atoms of opposite type (Ni and O)
were energetically comfortable when they were next to each other.
Energy of the system increased when atoms of same type were
closer together across the grain boundary. 
One oxygen atom in the grain boundary was
replaced with a vacancy. It is the site
that is marked as 'V' in Figure 1.
Nearby oxygen atoms were then moved into this
vacant site one at a time. Ten intermediate
positions of this moving atom were
investigated by holding the atom fixed and
relaxing all other atoms around it (NIX principle).
The energy of
of the whole system at every step for this moving atom
was stored and plotted. Figure 2 shows the energy
chnages of the system when each of the atoms
was moved using NIX principle.
The numbers indicate the position of the oxygen atoms
moved. The energy plot for each corresponding atom is
shown in Figure 2. Minimum energy barrier was
observed for atom number 6. The migration
energy barrier was about 0.5 eV.
Anjali Nandedkar, Ph. D.
CASA Engineering
15 Dartantra Drive
Hopewell Junction
NY 12533
U.S.A
Tel. and FAX: (845) 226 - 1925
anjali@casaengineering.com