1. First Principles Kinetic Monte Carlo
Simulations of Oxygen Interaction with
LaMnO3 Perovskite Surface
Ghanshyam Pilania and R. Ramprasad
Institute of Materials Science,
University of Connecticut
MRS Fall Meeting 2011
SESSION B10/C6: Joint Session: SOFC Materials Characterization II

2. Oxygen Interactions with Perovskites:
Applications
Solid oxide fuel cells NO oxidation Photocatalytic H2O
splitting
O2 H2
Catalytic H2O H2O
Converter
O2
Sr doped Triple-phase
LaMnO3 boundary
O-2
YSZ
J. Fleig, Annu. Rev. Mater. Res. 33, 361 (2003). Chang Hwan Kim, et al. Science 327, 1624 (2010) Kudo et al. Chem. Soc. Rev., 2009, 38, 253–278

3. Relevant Elementary Processes
Molecular adsorption
Molecular desorption
Dissociative adsorption
Associative desorption
Surface dissociation
Surface Association
Surface Diffusion

4. First Principles Thermodynamics
(FPT)
O covered surface configurations
O2 covered surface configurations

5. First Principles Thermodynamics
(FPT)
Surface Energy
Oxygen Chemical Potential

6. First Principles Thermodynamics
partial'coverage'-
O2#Condensation##
of'atomic'O
O2#partial#pressure##[log10(p/p0)]6
100#%#O#
Clean&surface
Temperature)(K)-

7. Limitations of the FPT approach
•Configurational entropy is not taken into
account
•Treatment of “large” systems may not
be practical
•Metastability can not be captured
•Kinetic aspects

8. Kinetic Monte Carlo Simulations
Method Highlights
•DFT fitted 2-D lattice gas Hamiltonian
•Lateral interactions between the
adsorbates
•Activation barriers within DFT nudged
elastic band Method
•Local environment dependent activation
barriers

9. Kinetic Monte Carlo Simulations
Thermodynamic Phase diagram
partial'coverage'- partial'coverage'-
O2#Condensation## of'atomic'O O2#Condensation##
of'atomic'O
O2#partial#pressure##[log10(p/p0)]6
O2$partial$pressure$$[log10(p/p0)]7
100%$O
100#%#O# 100#%#O#
Clean&surface
Clean&surface
Temperature$(K)7 Temperature)(K)-
Saracco, G., Geobaldo, F. (1999). Applied Catalysis B: Environmental.

10. Kinetic Monte Carlo Simulations
“Metastable” Phase diagrams
O+O2 partial'coverage'- partial'coverage'-
O2#Condensation## covered of'atomic'O O2#Condensation## of'atomic'O
100#%#O# 100#%#O#
100%O2
O+O2
Clean surface Clean surface
Starting from a clean surface at 100 K and
Starting from a clean surface at any given
ramping up the temperature at a given
temperature and pressure.
pressure.
R. Spinicci et al. Journal of Molecular Catalysis A: Chemical 197 (2003) 147–155

11. BECAT
THANKS!