Lecture

Symmetry and Group Theory

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In course

CH-250: Mathematical methods in chemistry

This course consists of two parts. The first part covers basic concepts of molecular symmetry and the application of group theory to describe it. The second part introduces Laplace transforms and Fourier series and their use for solving ordinary and partia ...

Description

This lecture covers topics related to symmetry and group theory, focusing on the application of group theory in chemistry. The content includes identifying symmetry elements in molecules, matrix representations for reflections, rotation matrices, and normal modes. The lecture also delves into the concept of irreducible representations, normal coordinates, and the separation of the harmonic oscillator problem. Practical exercises and examples are provided to enhance understanding.

Instructors (2)

Ulrich Lorenz

Teaching & PhD PhD Students Jakub Hruby Past EPFL PhD Students Pavel Olshin, Gabriele Bongiovanni, Chengcheng Yan, Oliver Florian Harder, Mowry Nathan Junior, Constantin Richard Krüger

Jiri Vanicek

Teaching & PhD PhD Students Liam Oliver Marsh, Yeha Lee, Davide Barbiero, Yannick Calvino Alonso, Manas Nagda Past EPFL PhD Students Cesare Mollica, Ray Marcel Marin Florez, Marius Wehrle, Aurélien Patoz, Konstantin Karandashev, Tomislav Begusic, Julien Roulet, Seonghoon Choi, Roya Moghaddasi Fereidani, Zhan Tong Zhang, Eriks Kletnieks, Alan Scheidegger, Fabian Kröninger Courses Mathematical methods in chemistry CH-250 This course consists of two parts. The first part covers basic concepts

Official source

Related concepts (32)

Symmetry

Symmetry () in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, the term has a more precise definition and is usually used to refer to an object that is invariant under some transformations, such as translation, reflection, rotation, or scaling. Although these two meanings of the word can sometimes be told apart, they are intricately related, and hence are discussed together in this article.

Point group

In geometry, a point group is a mathematical group of symmetry operations (isometries in a Euclidean space) that have a fixed point in common. The coordinate origin of the Euclidean space is conventionally taken to be a fixed point, and every point group in dimension d is then a subgroup of the orthogonal group O(d). Point groups are used to describe the symmetries of geometric figures and physical objects such as molecules. Each point group can be represented as sets of orthogonal matrices M that transform point x into point y according to y = Mx.

Symmetry group

In group theory, the symmetry group of a geometric object is the group of all transformations under which the object is invariant, endowed with the group operation of composition. Such a transformation is an invertible mapping of the ambient space which takes the object to itself, and which preserves all the relevant structure of the object. A frequent notation for the symmetry group of an object X is G = Sym(X). For an object in a metric space, its symmetries form a subgroup of the isometry group of the ambient space.

Molecular symmetry

In chemistry, molecular symmetry describes the symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties, such as whether or not it has a dipole moment, as well as its allowed spectroscopic transitions. To do this it is necessary to use group theory. This involves classifying the states of the molecule using the irreducible representations from the character table of the symmetry group of the molecule.

Character table

In group theory, a branch of abstract algebra, a character table is a two-dimensional table whose rows correspond to irreducible representations, and whose columns correspond to conjugacy classes of group elements. The entries consist of characters, the traces of the matrices representing group elements of the column's class in the given row's group representation. In chemistry, crystallography, and spectroscopy, character tables of point groups are used to classify e.g.

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