First-Principles Study of Domain Evolution of IR on IR(111)

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Habar ◽  
S. Ouannasser ◽  
L. Stauffer ◽  
H. Dreyssé ◽  
L. T. Wille
Keyword(s):  
First Principles ◽  
Tight Binding ◽  
Diffusion Barriers ◽  
Domain Growth ◽  
Zero Temperature ◽  
Adsorption Sites ◽  
Surface Sites ◽  
Kinetics Of ◽  
Entropic Effects ◽  
Effective Cluster

ABSTRACTWe have calculated the effective cluster interactions (ECI) which govern the ordering of Ir adatoms on the Ir(111) surface. The computations are based on a tight-binding Hamiltonian in which no adjustable or experimentally determined parameters were introduced. Both atoms adsorbed in ‘bulk’ sites (i.e. continuing the fee lattice) and those in ‘surface’ sites (i.e. producing hep stacking) are considered. We use this formalism to determine the relative stability of various adsorption sites and cluster shapes at zero temperature. The overall trends are in excellent agreement with the experimental results found by Ehrlich and co-workers. Next, we employ these ECI in Monte Carlo simulations of the kinetics of domain growth and evolution. Specifically we analyze the effect of diffusion barriers and the competition between the ordering tendencies of the system and entropic effects. Typical ‘snapshots’ in a range of temperatures and coverages are discussed.

Kinetics of Surface Segregation in Metallic Alloys with First-Principles Interaction Parameters

1995 ◽  
Vol 398 ◽  
Author(s):  
L. T. Wille ◽  
S. Ouannasser ◽  
H. Dreyssé
Keyword(s):  
First Principles ◽  
Surface Segregation ◽  
Tight Binding ◽  
Surface Region ◽  
Electronic Structure Calculations ◽  
Segregation Behavior ◽  
Kinetics Of ◽  
Structure Calculations ◽  
Effective Cluster ◽  
Equilibrium Segregation

ABSTRACTWe report the results of Monte Carlo simulations of the kinetics of surface segregation at the (001) face of CuNi and MoW alloys. These two systems were selected because they are based on different lattice structures and show contrasting segregation behavior: CuNi exhibits a monotonie profile, while that of MoW is oscillatory. To describe the energetics we have determined a set of effective cluster interactions (ECI) which govern the ordering or clustering tendencies of these alloys. The ECI were obtained by means of tight-binding electronic structure calculations in which no adjustable or experimentally determined parameters were used. Equilibrium segregation profiles are calculated and a series of quenches are performed. The layer concentrations are studied as a function of time and the existence of metastable phases in the surface region is investigated.

MICROSCOPIC THEORY AND SIMULATION OF ADATOM DIFFUSION ON Ir(111)

1997 ◽  
Vol 04 (05) ◽  
pp. 851-854 ◽  
Author(s):  
S. OUANNASSER ◽  
M. HABAR ◽  
L. STAUFFER ◽  
H. DREYSSÉ ◽  
L. T. WILLE
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Relative Stability ◽  
Tight Binding ◽  
Microscopic Theory ◽  
Diffusion Behavior ◽  
Surface Sites ◽  
Adatom Diffusion ◽  
Effective Cluster

Using a realistic tight-binding Hamiltonian we have calculated the effective cluster interactions that describe the ordering of adsorbed Ir atoms on the Ir (111) surface. We have determined the relative stability of adatoms in "bulk" and "surface" sites and also mapped out the barrier between them. This information is then used as input in Monte Carlo simulations which allow us to determine typical diffusion behavior at various temperatures.

Designing Chemically Selective Liquid Crystalline Materials that Respond to Oxidizing Gases

2021 ◽  
Author(s):  
Nanqi Bao ◽  
Jake Gold ◽  
Tibor Szilvasi ◽  
Huaizhe Yu ◽  
Robert Twieg ◽  
...  
Keyword(s):  
Computational Methods ◽  
First Principles ◽  
Liquid Crystalline ◽  
Soft Materials ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Chemically Selective ◽  
Kinetics Of

Computational methods can provide first-principles insights into the thermochemistry and kinetics of reactions at interfaces, but this capability has not been widely leveraged to design soft materials that respond selectively...

scholarly journals Rheological behaviour and aggregation kinetics of EG/water based MCNT nano-suspension for sub-zero temperature cold storage

2019 ◽  
Vol 158 ◽  
pp. 4846-4851
Author(s):  
Yaoting Huang ◽  
Chunping Xie ◽  
Chuan Li ◽  
Yongliang Li ◽  
Yulong Ding
Keyword(s):  
Cold Storage ◽  
Rheological Behaviour ◽  
Aggregation Kinetics ◽  
Zero Temperature ◽  
Water Based ◽  
Kinetics Of
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