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Next: Why boron nitride polymers? Up: Material design from first Previous: Material design from first

Introduction

Recent advances in synthesis and nanofabrication technologies have dramatically broadened the range of materials that can be designed with desired and controlled characteristics. In parallel with these developments, improvements in computer simulation algorithms and the availability of powerful computers offer a complementary way to probe the properties of potentially interesting materials, even before (or without) making them in the laboratory. In particular, first-principles methods (whose input parameters consist only of a list of the atoms in the system, and which then solve the Schrödinger equation for the interacting electrons in the potential of the nuclei) are a powerful and unbiased tool for predicting the behaviour of new materials at the atomistic level. Among first-principles techniques, density-functional theory (DFT), which is a modern reformulation of quantum mechanics in terms of the electron density [1,2], offers a favorable ratio between accuracy and computational cost, which makes it suitable for (relatively) large scale calculations. Its success in describing structural and electronic properties of real materials has been recognized by the award of the 1998 Nobel Prize in Chemistry to its founder, Walter Kohn [3]. It has been combined with molecular dynamics, thus allowing the simulation of systems at finite temperature [4,5]. Because of the absence of empirical parameters, DFT is suitable for applications in very diverse fields, from materials science to biochemistry [6,7]. In particular, various properties of polymers have been studied with such a method (see e.g. Refs. [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25] ). DFT accuracy has a price, which nowadays limits size and simulation time to a few hundreds atoms and a few picoseconds. On the one hand, this is sufficient to study many properties successfully, as testified by the thousands of published papers on DFT applications [7]; on the other, it is spurring on the development of new methods for overcoming the scale and size limitations [26], as well as other pitfalls mainly due to the description of the troublesome electron exchange and correlation. In this paper, we present an example of how state-of-the-art DFT calculations can be used to analyze the properties of a series of hypothetical systems, designed using BN polymers as building blocks [27]. For a preliminary screening, making these polymers in a ``virtual matter laboratory'' [28] is easier, cleaner and less dangerous than trying to make them in a real laboratory.
next up previous
Next: Why boron nitride polymers? Up: Material design from first Previous: Material design from first
Peter D. Haynes 2002-10-28