M.F. Thorpe - Böcker

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, materials science and engineering, with length scales ranging from Ångstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up-to-date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M.F. Thorpe, Series Editor E-mail: thorpe @ pa.msu.edu East Lansing, Michigan PREFACE One of the most challenging problems in the study of structure is to characterize the atomic short-range order in materials. Long-range order can be determined with a high degree of accuracy by analyzing Bragg peak positions and intensities in data from single crystals or powders. However, information about short-range order is contained in the diffuse scattering intensity. This is difficult to analyze because it is low in absolute intensity (though the integrated intensity may be significant) and widely spread in reciprocal space.

Although rigidity has been studied since the time of Lagrange (1788) and Maxwell (1864), it is only in the last 25 years that it has begun to find applications in the basic sciences. The modern era starts with Laman (1970), who made the subject rigorous in two dimensions, followed by the development of computer algorithms that can test over a million sites in seconds and find the rigid regions, and the associated pivots, leading to many applications. This workshop was organized to bring together leading researchers studying the underlying theory, and to explore the various areas of science where applications of these ideas are being implemented.

Advances in nanoscale science show that the properties of many materials are dominated by internal structures. In molecular cases, such as window glass and proteins, these internal structures obviously have a network character. However, in many partly disordered electronic materials, almost all attempts at understanding are based on traditional continuum models. This volume focuses first on the phase diagrams and phase transitions of materials known to be composed of molecular networks. These phase properties characteristically contain remarkable features, such as intermediate phases that lead to reversibility windows in glass transitions as functions of composition. These features arise as a result of self-organization of the internal structures of the intermediate phases. In the protein case, this self-organization is the basis for protein folding. The second focus is on partly disordered electronic materials whose phase properties exhibit the same remarkable features. In fact, the phenomenon of high temperature superconductivity, discovered by Bednorz and Mueller in 1986, and now the subject of 75,000 research papers, also arises from such an intermediate phase.More recently discovered electronic phenomena, such as giant magnetoresistance, also are made possible only by the existence of such special phases. This book gives an overview of the methods and results obtained so far by studying the characteristics and properties of nanoscale self-organized networks. It demonstrates the universality of the network approach over a range of disciplines, from protein folding to the newest electronic materials.

This workshop brought together researchers from materials science, physics, chemistry and biochemistry with interests in determining the structure of substances beyond their average crystal structure. Materials where this is important range from semiconductor alloys to proteins in solution. It featured pedagogical talks on the analysis of diffuse scattering from single crystals and powders, XAFS, NMR, small angle scattering and other techniques which reveal additional information about materials beyond that obtained by Bragg analysis. Theory plays a special role in such studies because of the difficulty of extracting and interpreting information from these techniques.

The papers in this volume are from the workshop on Protein Flexibility and Folding held in Traverse City, Michigan from August 13 - 17, 2000. The purpose of the workshop was to bring together diverse people interested in protein folding and flexibility from theoretical, computational and experimental perspectives and to encourage discussion on new approaches and challenges in the field. The workshop was held in the Park Plaza Hotel with 43 participants, including 24 invited speakers. The small size of the group made for easy exchanges, and many of the presentations by the invited speakers appear in this volume. There was also a very lively poster session.The three-day workshop was organized so that the first day covered Flexibility and Dynamics, the second day Folding and Unfolding, and the third day Evolution and Design. This area of science is particularly appealing as it spans a range of questions from very fundamental - as to how proteins fold in such short times with such reliability - to applications such as the role of flexibility in screening for new ligands to a protein. Protein flexibility and folding have attracted the attention of scientists from many disciplines, ranging from mathematics to molecular biology. The scientists at the workshop represented the breadth of challenges in theory and applications that keep this field so fascinating and dynamic.The present volume is organized along these same lines.

This work is organized into four sections, starting with general considerations of glass forming ability and techniques for the preparation of different kinds of glasses. There has been activity on the nature of the glass transition in recent years, but it remains a difficult and poorly understood subject. The second section discusses the various techniques used to investigate the structure of the glasses, including extensive notes on computer simulation techniques. The third section goes into vibrational states, with special emphasis on the interaction between theory and experiment. In the final section the electronic structure of the glasses is reviewed, together with its relationship with their electrical properties, which involves an understanding of defects. Also included in this section is a review of current thinking on tunnelling states in glasses.

The particular interest represented in this state-of-the art survey of amorphous materials is their electronic properties and device applications. The book is organized in five sections, starting with some more unusual aspects of structure. Section 2 deals with the area of self organization in glasses and how this relates to a glass`s rigidity. The next section surveys electronic states and transport phenomena. The fourth section deals with an area of photo-induced effects that has recently seen increased interest due to possible device applications. Finally, section 5 covers some properties specific to amorphous silicon and amorphous carbon.

The particular interest represented in this state-of-the art survey of amorphous materials is their electronic properties and device applications. The book is organized in five sections, starting with some more unusual aspects of structure. Section 2 deals with the area of self organization in glasses and how this relates to a glass`s rigidity. The next section surveys electronic states and transport phenomena. The fourth section deals with an area of photo-induced effects that has recently seen increased interest due to possible device applications. Finally, section 5 covers some properties specific to amorphous silicon and amorphous carbon.

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, materials science and engineering, with length scales ranging from Ångstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up-to-date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M.F. Thorpe, Series Editor E-mail: thorpe @ pa.msu.edu East Lansing, Michigan PREFACE One of the most challenging problems in the study of structure is to characterize the atomic short-range order in materials. Long-range order can be determined with a high degree of accuracy by analyzing Bragg peak positions and intensities in data from single crystals or powders. However, information about short-range order is contained in the diffuse scattering intensity. This is difficult to analyze because it is low in absolute intensity (though the integrated intensity may be significant) and widely spread in reciprocal space.

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, materials science, and engineering, with length scales ranging from Angstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up-to-date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M.F. Thorpe, Series Editor E-mail: thorpe@pa.msu.edu East Lansing, Michigan, November 200 I v PREFACE The study of the atomic structure of crystalline materials began at the beginning of the twentieth century with the discovery by Max von Laue and by W.H. and W.L. Bragg that crystals diffract x-rays. At that time, even the existence of atoms was controversial.

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, and engineering, with length scales ranging from Ångstromsup to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area ofcurrent interest and brings together leading experts to give an up-to-date discussion of their work and the work ofothers. Each article contains enough references that the interested reader can accesstherelevant literature. Thanks aregiven to the Center forFundamental Materials Research atMichigan State University forsupportingthis series. M.F. Thorpe, Series Editor E-mail: thorpe@pa.msu.edu EastLansing,Michigan, September, 1995 PREFACE This book records selected papers given at an interdisciplinary Symposium on Access in Nanoporous Materials held in Lansing, Michigan, on June 7-9, 1995. Broad interest in the synthesis of ordered materials with pore sizes in the 1.0-10 nm range was clearly manifested in the 64 invited and contributed papers presented by workers in the formal fields of chemistry, physics, and engineering. The intent of the symposium was to bring together a small number ofleading researchers within complementary disciplines to share in the diversity of approaches to nanoporous materials synthesis and characterization.

Although rigidity has been studied since the time of Lagrange (1788) and Maxwell (1864), it is only in the last twenty-five years that it has begun to find applications in the basic sciences. The modern era starts with Laman (1970), who made the subject rigorous in two dimensions, followed by the development of computer algorithms that can test over a million sites in seconds and find the rigid regions, and the associated pivots, leading to many applications. This workshop was organized to bring together leading researchers studying the underlying theory, and to explore the various areas of science where applications of these ideas are being implemented.

Advances in nanoscale science show that the properties of many materials are dominated by internal structures. In molecular cases, such as window glass and proteins, these internal structures obviously have a network character. However, in many partly disordered electronic materials, almost all attempts at understanding are based on traditional continuum models. This workshop focuses first on the phase diagrams and phase transitions of materials known to be composed of molecular networks. These phase properties characteristically contain remarkable features, such as intermediate phases that lead to reversibility windows in glass transitions as functions of composition. These features arise as a result of self-organization of the internal structures of the intermediate phases. In the protein case, this self-organization is the basis for protein folding. The second focus is on partly disordered electronic materials whose phase properties exhibit the same remarkable features. In fact, the phenomenon of High Temperature Superconductivity, discovered by Bednorz and Mueller in 1986, and now the subject of 75,000 research papers, also arises from such an intermediate phase. More recently discovered electronic phenomena, such as giant magnetoresistance, also are made possible only by the existence of such special phases. This book gives an overview of the methods and results obtained so far by studying the characteristics and properties of nanoscale self-organized networks. It demonstrates the universality of the network approach over a range of disciplines, from protein folding to the newest electronic materials.