Abstract:
The atomistic simulations in the framework of the Generalized Simulated
Annealing approach (GSA) and classical force fields lead to very reasonable
relaxed geometries around the carbon interstitial in O-, T-, and TS-sites.
We have thus shown that a highly efficient energy-sampling and relaxation
scheme, implemented with tight constraints on a limited volume, provides
a powerful steering mechanism for selection of geometries suitable for
detailed investigation by first-principles methods. The results, based
upon harmonic interactions between Cu atoms and a van der Waals interaction
between Cu and C, predict the relaxed O-site to be more stable than the
T-site by similar to 1.2 eV, in accordance with general expectations.
The TS barrier to O-O diffusion is found to be similar to 0.8 eV, at a
temperature of 0 K; the TS exhibits a strong local axial distortion of
the pseudo-octahedral environment. The Density Functional results indicate
a charge transfer of similar to 1 e to carbon, mostly from the first neighbor
shell, in all relaxed environments studied. Bond-order data show the Cu-C
interaction to be bonding in nature, despite the net 'repulsive interaction'
leading to a surface state of lower net energy.
KeyWords Plus: EMBEDDED-CLUSTER MODEL, ALLOYS
Addresses:
Ellis DE, Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208
USA.
Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208 USA.
Univ Bahja, Inst Phys, Salvador, BA, Brazil.
Technion Israel Inst Technol, Dept Phys, IL-32000 Haifa, Israel.
Technion Israel Inst Technol, Dept Mat Engn, IL-32000 Haifa, Israel.
Publisher :
ELSEVIER SCI LTD, OXFORD
IDS Number : 358EX
ISSN
: 1369-8001