ABSTRACT

References............................................................................ 104

2.1 INTRODUCTION

This article could have been subtitled “The Right Question for the Right Reason.”1 Part of our purpose is to review the computational methods widely available to the photochemist today, which the authors have used extensively over the past decade.2 But we also have a second purpose: to give some guidelines (based on experience) concerning the kind of questions about photochemistry that these methods can usefully answer. The authors are often approached with the request, “Can you do some calculations on…?” The answer may be yes, but what is the question that really needs answering? Is it a question about the excitation spectrum (what state is that?) or reaction mechanism (why doesn’t that product form?). Having the right question is at least as important as knowing how to use the available methods, as we hope to show using examples drawn from recent work.