Doublon Production in Correlated Materials by Multiple Ion Impacts

Abstract

Recently, it was demonstrated that ions impacting a correlated finite graphene‐type honeycomb cluster can excite strong nonequilibrium states. In particular, this can lead to an enhanced population of bound pairs of electrons with opposite spin—doublons—where the doublon number can be increased further via multiple ion impacts. These predictions were made based on nonequilibrium Green functions (NEGF) simulations allowing for a time‐dependent non‐perturbative study of the energy loss of charged particles penetrating a strongly correlated system. Herein, these simulations are extended to larger clusters and longer simulation times, utilizing the recently developed G1–G2 scheme, which allows for a dramatic speedup of NEGF simulations. Furthermore, the dependence of the energy and doublon number on the time interval between ion impacts and on the impact point is investigated.

Time-linear scaling nonequilibrium Green's function methods for real-time simulations of interacting electrons and bosons. I. Formalism

“…Furthermore, the inclusion of an interaction with a fermionic or bosonic bath would make possible to simulate the dynamics of, e.g., photoionized systems [67,68] or molecular junctions [41,69]. Numerical works based on the GKBA+ODE scheme have begun to appear in the literature only recently [47][48][49]. Parallel implementations in high performance computer facilities are expected to open the door to first-principles investigations of a wide range of nonequilibrium correlated phenomena.…”

“…One can work either with the integro-differential formulation, which has a quadratic (t 2 f ) scaling in time [38][39][40][41][42][43][44], or with a coupled system of first-order ordinary differential equations (ODE) thus achieving a linear (t f ) time scaling [45,46]. The linear-time formulation has been already implemented to study the photoinduced dynamics of organic molecules [47], carrier and exciton dynamics in 2D materials [48], and the doublon production in correlated graphene clusters [49].…”

Topological Defects Created by Gamma Rays in a Carbon Nanotube Bilayer

“…It was assumed in [ 34 ] that the ICD can mimic the explosive divergence of two repulsive bound electrons in an atomic cluster. An approach using a Hubbard-type Hamiltonian model (the Hartree approximation without taking into account the Fock exchange term) to describe the repulsive bound electron state was based on the quantum-field picture, which assumes that a cloud of virtual fermionic excitation pairs exists in the same lattice site (see [ 35 , 36 ] and references therein).…”