Multiscale simulation of cluster growth and deposition processes by hybrid model based on direct simulation Monte Carlo method Hiroshi Mizuseki a, * , Kenta Hongo a , Yoshiyuki Kawazoe a , Luc T. Wille b a Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan b Department of Physics, Florida Atlantic University, Boca Raton, FL 33431, USA Abstract A cluster growth and deposition model based on hybrid modeling is introduced to examine the experimental con- ditions of the cluster growth process in vacuum chamber and deposition process on substrate. This hybrid model is a simulation method including physical length and time scale characteristics of macro and microscale. We simulated the behavior of the cluster during the flight path by direct simulation Monte Carlo (DSMC) method and the deposition behavior on the substrate by a simple MC model. Several size distributions of the clusters and various morphologies of deposited film were obtained, and the relationship between macroscopic and microscopic physical phenomena during deposition process was examined. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 81.15.Aa; 81.15.Jj; 81.16.Mk 1. Introduction Cluster assembly has emerged as one of the leading candidates to manufacture nanostructured materials with tight control over desired proper- ties, while permitting fast production time [1,2]. Application areas of such structures range from magnetic recording media [3] to semiconductor quantum dots [4]. A theoretical understanding of these nanoassembled materials necessitates an analysis of the cluster growth process from the vapor phase, as well as a description of the depo- sition and subsequent time evolution. This is clearly a challenging problem, both from a fun- damental point of view and in consideration of the computational obstacles that need to be over- come. Moreover, the processes involved operate over orders of magnitude in time and length scales. In the present paper, we discuss results of large- scale computer simulations of cluster growth fol- lowed by deposition. For the former, the direct simulation Monte Carlo (DSMC) method is used, while for the latter a MC simulation is performed. Because the properties of the deposited film depend critically on the size distribution and con- formations of the impinging clusters, it is essential to describe cluster nucleation and growth accu- rately. The main experimental technique to pro- duce atomic clusters is based on an adiabatic expansion of a monoatomic gas in the presence of Computational Materials Science 24 (2002) 88–92 www.elsevier.com/locate/commatsci * Corresponding author. Fax: +81-22-215-2052. E-mail address: mizuseki@imr.edu (H. Mizuseki). 0927-0256/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S0927-0256(02)00168-4