Karl Franzens University Graz
Graz University of Technology
|
|
| |
Karl Franzens University Graz | Graz University of Technology | |
Can we use quantum mechanics but avoid the wavefunction? An introduction to the ups and downs of density functional theory Whenever we intend to calculate properties of a many particle system - e.g., the electronic structure of a molecule or solid - we face the challenge that in principle all we would need to do is solve the many particle Schrödinger equation - but while writing down the equation is easy, it is exceedingly hard to solve it in practice. The complexity of calculating the correlated many particle wavefunction thus seriously limits the use of quantum mechanics "in its usual form" for problems in physics and material science. Density Functional Theory is a very popular and powerful alternative formulation of quantum mechanics that allows for circumventing the many particle wavefunction. It has emerged as one of the most successful and widely used theories for studying problems of electronic structure and dynamics in physics, chemistry and material science. The talk will present some examples from nano particle research in which Density Functional Theory has lead to important insights. However, besides its successes, the theory also has its peculiarities as a consequence of avoiding the wavefunction. The talk will demonstrate how the strengths and quandaries of Density Functional Theory affect its use in the important area of organic solar cell research. Specifically, the topic of probing organic semiconductors by photo emission spectroscopy and interpreting the results based on Density Functional calculations will be addressed. |