Use ADESH to Calculate the Defect Configurations
adesh.zip :Click here to Download a DEMO version of ADESH
(ADESH works on PC-DOS. You will need the pkunzip.exe utility
for this zipped file. ADESH works on MAC and UNIX workstations
in a DOS window)ADESH calculates the energy of the configurations using appropriate potential energy functions.
Configurations can be relaxed using numerical techniques like Static, Monte-Carlo, Simulated Annealing
Point Defects: Vacancy
This is a vacancy in aluminum. The orientation of the
cell is X(1 0 0), Y(0 1 0) and Z (0 0 1).
ADESH uses this cell with a vacant site to
calculate vacancy formation energy and vacancy migration energy.
Point Defects: Impurities, Alloying Elements
Red copper atoms are randomly distributed in an aluminum cell
(green atoms). We studied interactions of copper with defects
in aluminum. The copper atoms segregated
near grain boundaries and dislocations in aluminum.
Swap technique was used to study the segregation.
Line Defect: Dislocation
This is a 90 degree
dislocation in silicon: (1/2<110>{001}|<110>) Migration
energy of this dislocation was calculated with ADESH.
It was about 2 eV. Surprisingly, this activation energy for
migration is similar to the 60 degree dislocation in silicon.
Observe the migration of this dislocation through animation.
(You can also observe nucleation of a misfit dislocation at a
Hetero-Junction.)
(These animations need Netscape 2.0 or higher for viewing.)
Surface Defect: Grain Boundary
This is a tilt boundary in silicon (Sigma=5, Angle = 38.94 Deg.).
ADESH created the configuration in about one minute.
Minimizing the energy took about twenty minutes more on a PC
with 486 microprocessor.
Questions? Comments? Suggestions?
Send a note to Anjali Nandedkar at CASA Engineering
Anjali Nandedkar, Ph. D.
CASA Engineering
15 Dartantra Drive
Hopewell Junction
NY 12533
U.S.A
Tel.:(845) 226 - 1925
anjali@casaengineering.com
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