Random phase approximation for materials modelling: melting point of Si

Beschreibung

The random phase approximation (RPA) to the correlation energy is among the most promising methods to obtain accurate correlation energy differences at reasonable computational cost, in particular, for solid state systems. Here, I review recent methodological advances as well as applications of the RPA. Specifically, a cubic system size scaling can be obtained using a real-space imaginary time representation reducing the computation time by typically one to two order of magnitude for large systems. Furthermore, the scaling with respect to the number of k points used to sample the Brillouin zone can be reduced to linear order.
This now allows to consider materials science problems using the RPA. I present calculations of the melting point of Si, using three different functional, PBE, HSE and SCAN as well as the RPA. For the RPA, a melting temperature of about 1735 K and 1640 K without and with core polarization effects, respectively, is found. Both values are within 3% of the experimental melting temperature of 1687 K. In comparison, the commonly used gradient approximation to density functional theory predicts a melting point that is 200 K too low, and hybrid functionals overestimate the melting point by 150 K. The predicted melting point is correlated to the energy difference between cubic diamond and the beta-tin phase of silicon.

Zeitraum	4 Apr. 2018
Ereignistitel	From Electrons to Phase Transitions 2018: A ViCoM Conference
Veranstaltungstyp	Konferenz
Ort	Vienna, ÖsterreichAuf Karte anzeigen
Bekanntheitsgrad	International