Structural Database for Reducing Cost in Materials Design and Complexity of Multiscale Computations NIKOLAI ZARKEVICH Materials Science and Engineering Department, University of Illinois at Urbana-Champaign, Urbana, IL 61801 Received September 30, 2005; revised November 30, 2005; accepted November 30, 2005 Computational complexity of multiscale methods based on the first-principles energetics is analyzed. Compu- tational cost of such methods is dominated by expensive first-principles determination of structural energies and atomic forces, including structural relaxations. Information integration is an opportunity to eliminate recal- culation of known data, and, consequently, to reduce the total cost of multiscale calculations. We propose the Structural Database as a universal tool for structural data integration, and explain its conceptual design and functionality, including data mining options. To exemplify benefits provided by the Structural Database, we consider search for new ground states, construction of a phase diagram for a bulk material, and prediction of surface patterning. We show that the Structural Database is a powerful tool for information integration and data mining, which can greatly reduce the cost of multiscale computations and materials design. © 2006 Wiley Periodicals, Inc. Complexity 11: 36 – 42, 2006 Key Words: computational complexity; multiscale calculations; data mining 1. INTRODUCTION W e live in a material world. We are surrounded by material objects. In our everyday life we use tools made of various materials. These tools make our life good and comfortable. Do we need better materials for better life? The answer is: yes! If we look back in the history of mankind, we can find that the first tools used by humans were made from wood and stones. Later people discovered that bronze (iron) is a better material for knifes than stone, and the Stone Age changed to the Bronze, and later to the Iron Age. Better materials resulted in better tools and better life. Today we have a large number of different materials in our tools, but scientists still aggressively search for novel materials with desired (new or improved) properties in or- der to make our life better. This search (materials design) is not an easy task: it involves costly experiments, theoretical Correspondence to: Nikolai Zarkevich, E-mail: zarkevic@ uiuc.edu 36 COMPLEXITY © 2006 Wiley Periodicals, Inc., Vol. 11, No. 4 DOI 10.1002/cplx.20117