On the computation of electronic excitations in solids

Peter Horsch, Peter Fulde

Seb J. Savory

We demonstrate in a solid state quantum gate based on the electronic excitation of a control atom that it is possible to disentangle the control electron, in the presence of an arbitrary magnetic field and exchange interaction. This will allow multiple gates on a single substrate, providing the basis for a solid state quantum computer.

Evgeny Moerman, Henrique Pereira Coutada Miranda, Alejandro Gallo +7 more

While the periodic equation-of-motion coupled-cluster (EOM-CC) method promises systematic improvement of electronic band gap calculations in solids, its practical application at the singles and doubles level (EOM-CCSD) is hindered by severe finite-size errors in feasible simulation cells. We present a hybrid approach combining EOM-CCSD with the computationally less demanding G W approximation to estimate thermodynamic limit band gaps for several insulators and semiconductors. Our method substantially reduces required cell sizes while maintaining accuracy. Comparisons with experimental gaps and self-consistent G W calculations reveal that deviations in EOM-CCSD predictions correlate with reduced single excitation character of the excited many-electron states. Our work not only provides a computationally tractable approach to EOM-CC calculations in solids but also reveals fundamental insights into the role of single excitations in electronic-structure theory.

George H. Booth, Andreas Grüneis, Georg Kresse +1 more

Chao Lian, Shiqi Hu, Mengxue Guan +1 more

Ultrafast electronic dynamics in solids lies at the core of modern condensed matter and materials physics. To build up a practical \textit{ab initio} method for studying solids under photoexcitation, we develop momentum-resolved real-time time dependent density functional theory (rt-TDDFT) algorithm using numerical atomic basis, together with the implementation of both length and vector gauge of electromagnetic field. When applied to simulate elementary excitations in graphene, different excitation modes, only distinguishable in momentum space, are observed. The momentum-resolved rt-TDDFT is important and computationally efficient for the study of ultrafast dynamics in extended systems.

Peter Fulde