Finite-size scaling study of a lattice-gas model for oxygen chemisorbed on tungsten

P. A. Rikvold, K. Kaski, J. D. Gunton, and M. C. Yalabik
Phys. Rev. B 29, 6285 – Published 1 June 1984
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Abstract

We present a finite-size scaling study of a centered rectangular lattice-gas model with attractive nearest-neighbor interactions and repulsive second- and third-neighbor and three-particle interactions, as well as attractive fifth-neighbor interactions. This has been proposed as a model for atomic oxygen adsorbed on a (110) surface of tungsten. The ordered phases are a (2×1) phase with coverage 12 and a (2×2) phase with coverage 34. We obtain phase diagrams which are in good qualitative agreement with the available experimental information. This agreement is obtained with considerably weaker attractive fifth-neighbor interactions than previously suggested by ground-state and Monte Carlo calculations, but consistent with the results of quantum-mechanical band calculations. In particular, we find a multicritical point below which the low-coverage (2×1)-to-disorder transition is of first order. We also find indications of a previously undetected low-temperature multicritical point below which the high-coverage (2×2)-to-disorder transition may be of first order. The finite-size effects in this study are considerably stronger than in previous studies of simpler lattice-gas models. This limits the accuracy with which we can determine the multicritical temperatures. It also prevents us from obtaining reliable estimates of the nonuniversal critical exponents for this model.

  • Received 22 November 1983

DOI:https://doi.org/10.1103/PhysRevB.29.6285

©1984 American Physical Society

Authors & Affiliations

P. A. Rikvold*, K. Kaski, and J. D. Gunton

  • Physics Department, Temple University, Philadelphia, Pennsylvania 19122

M. C. Yalabik

  • Physics Department, Middle East Technical University, Ankara, Turkey

  • *Present address: Department of Mechanical Engineering, State University of New York at Stony Brook, Stony Brook, NY 11794.
  • Present address: Physics Department, Tampere University of Technology, P.O. Box 527, Tampere 10, Finland.

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Issue

Vol. 29, Iss. 11 — 1 June 1984

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