structural transitions in biomolecules - a numerical comparison of two approaches for the study of phase transitions in small systems在生物分子结构转换u2014u2014数值的比较两种方法研究相变在小系统.pdf

Int. J. Mol. Sci. 2002 , 3, 17-29 Int. J. Mol. Sci. ISSN 1422-0067 /ijms/ ”Dedicated to Prof. R.S. Berry on the occasion of his 70th Birthday” Structural transitions in biomolecules - a numerical com- parison of two approaches for the study of phase transi- tions in small systems † † Nelson A. Alves , Ulrich H.E. Hansmann and Yong Peng ´ ´ ˜ Departamento de Fısica e Matematica, FFCLRP Universidade de Sao Paulo. Avenida Bandeirantes ˜ 3900. CEP 014040-901 Ribeirao Preto, SP, Brazil E-mail: alves@quark.ffclrp.usp.br †Department of Physics, Michigan Technological University, Houghton, MI 49931-1291, USA E-mail: hansmann@ E-mail: ypeng@ Received: 22 October 2001 / Accepted : 26 January 2002 / Published: 31 January 2002 Abstract: We compare two recently proposed methods for the characterization of phase transitions in small systems. The usefulness of these techniques is evaluated for the case of structural transition in alanine-based peptides. Keywords: Phase transitions; Critical exponents; Partition function zeros; Helix-coil transi- tion. c 2002 by MDPI. Reproduction for noncommercial purposes permitted. Int. J. Mol. Sci. 2002 , 3 18 1 Introduction When phase transitions are studied in statistical physics, the basic assumption is usually that the di- mensions of the macroscopic system are very large compared with that of the constituting elements. However, there are