دانلود کتاب راهنمای شیمیدانان برای نظریه پیوند ظرفیتی – بینش‌هایی در مورد پیوند شیمیایی، واکنش‌پذیری و حالت‌های برانگیخته، ویرایش دوم

The first edition of A Chemist’s Guide to Valence Bond Theory was published in 2008, with the aim of filling the missing niche of a textbook that teaches valence bond (VB) theory. Indeed, VB theory that once had charted the mental map of chemists was practically abandoned since the mid-1960s for reasons that are discussed in Chapter 1. Consequently, the knowledge of VB theory became gradually scarcer and was effectively eliminated from the teaching curriculum in much of the chemical community. Nevertheless, the theory survived as the lingua franca of chemists, mostly due to the use of the Lewis bonding paradigm and the post-Lewis concepts of hybridization, covalent and ionic VB structures, and resonance. This was the situation up to the 1980s, when VB theory started to enjoy a renaissance that was characterized by the development of major ab initio VB methods and corresponding software, which could be routinely applied to chemical problems of bonding and reactivity (1–4). Moreover, alongside these methodology developments, there has been a surge of new post-Pauling models and concepts that have rendered VB theory useful again as a central theory in chemistry; especially productive concepts arose by importing insights from molecular orbital (MO) theory and making the VB approach more portable and easier to apply (2–4). As such, much has happened in the world of VB theory in the 17 years since we published the first edition of this book. On the conceptual side, new types of chemical bonding like charge-shift bonding or triplet-bond pairs have been discovered and discussed. On the computational side, existing methods like Valence-Bond Self-Consistent-Field (VBSCF) have been made faster and extended to apply to larger systems; this method has also been coupled with density functional theory (VBDFT) and Quantum Monte-Carlo Method (VB-QMC) so as to make it incorporate dynamic electron correlation. Additionally, the Breathing-Orbital VB (BOVB) method, which already included built-in dynamic correlation, was further adapted to photochemistry with a novel method of state-averaged calculations, showing for the first time that VB calculations could be way faster and much more compact than state-of-the-art standard methods based on molecular orbitals and configuration interaction (MO-CI) methods, for the same accuracy. Concomitantly, many papers have been published to account for these novel developments, among which are review articles (1–3), a recent major VB project of 22 chapters in the MRW series (4), monographs on theory and applications (5–7), and essays on VB theory and its relation to MO theory (8–10). As such, we felt that the time had come to write a second edition of our textbook (11) on VB theory and its computational methods, applications, and special insights. Like its predecessor (11), the present second edition is aimed at a nonexpert audience and designed as tutorial material for teachers and students who would like to teach and use VB theory, but who otherwise have basic knowledge of quantum chemistry. As such, the primary focus of this new edition is the provision of qualitative insight into the theory and ways of applying it to problems of bonding and reactivity in the ground and excited states of molecules. New material is added in the present edition on reactivity, bonding, and VB methodology. Almost every chapter contains problem sets followed by corresponding answer sets. These problems provide teachers, students, and interested readers with an opportunity to practice the art of VB theory. A new feature of the second edition involves two review chapters on general topics: [11] the chemical bond in VB theory, and [12] an updated description of the BOVB method that includes dynamic correlation. Another feature of this book is the description of the main methods and programs that are available today for ab initio VB calculations, and of the ways one may plan and run VB calculations. In this sense, the book provides a snapshot of the current VB capabilities in 2025. Regrettably, much important work had to be left out. The readers interested in technical and theoretical development aspects of VB theory may wish to consult two other monographs (5,6), as well as most of the chapters in the MRW project (4). We are thankful to all our co-workers and students during the years of collaboration (1981–2025). Especially intense collaborations with Dr. Benoît Braïda, Dr. Slavko Radenkovic and Professor Wei Wu, are acknowledged. Professor Wu is also thanked for making his program (XMVB) available to us throughout the past three decades.