## Matsubara frequency compression in warm dense matter

**Felix HUMMEL**

Institute for Theoretical Physics (ITP), Vienna University of Technology, Vienna, Austria

Mercredi 13 Novembre 2019, 11h00

bibliothèque LCT, tour 12 - 13, 4^{ème} étage

In warm dense matter as found for example in gas giants, electronic correlation is comparable to the thermal fluctuations *k*_{B}*T*. Accurately describing correlation in thermal systems poses a difficult problem facing many obstacles. One of them is the slow convergence of the infinite sum of Matsubara frequencies. Often, hundreds or thousands of frequencies are required for reasonably converged results. Matsubara compression schemes try to approximate the infinite sum by taking a smaller set of generally non-integer Matsubara frequencies having a non-unity weight. In the spirit of a recently proposed scheme for gapped systems [Kaltak et al. arxiv:1909.01740], a scheme is proposed which can also be applied to metallic systems. A few dozen frequency points provide sufficient accuracy and the finite temperature grid converges uniformly to a zero temperature grid, allowing calculations at arbitrarily low temperatures.