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

• Published in: Physical review. B, Condensed matter Condensed matter, 1984-06, Vol.29 (11), p.6285-6294
• Main Authors: RIKVOLD, P. A, KASKI, K, GUNTON, J. D, YALABIK, M. C
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; Materials science; Metals, semimetals and alloys; Metals. Metallurgy; Physics; Solid-gas interface; Specific materials; Surface physical chemistry
• ISSN: 0163-1829; 1095-3795
• DOI: 10.1103/PhysRevB.29.6285

A finite-size scaling study is presented of a centered rectangular lattice-gas model with attractive nearest-neighbor interactions and repulsive second- and third-neighbor and three-particle interactions and 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 x 1) phase with coverage 1/2 and a (2 x 2) phase with coverage 3/4. Phase diagrams were obtained 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, a multicritical point is found below which the low-coverage (2 x 1)-to-disorder transition is of first order. Indications of a previously undetected low-temp. multicritical point are also found below which the high-coverage (2 x 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 the multicritical temp. can be determined. 20 ref.--AA