Investigation of dense manifold of particle-hole excitations in metallic nanowires using r12-correlated frequency-dependent electron-hole interaction kernel

Abstract

Low-lying electronically excited states in metallic and semiconductor nanoparticles continue to be actively investigated because of their relevance in a wide variety of technological applications. However, first-principles electronic structure calculations on metallic and semiconductor nanoparticles are computationally challenging due to factors such as large system sizes, evaluation and transformation of matrix elements, and high density of particle-hole states. In this work, we present the development of the frequency-dependent explicitly-correlated electron-hole interaction kernel (FD-GSIK) to address the computation bottleneck associated with these calculations. The FD-GSIK method obtains a zeroth-order description of the dense manifold of particle-hole states by constructing a transformed set of dressed particle-holes states. Electron-hole correlation is introduced by using an explicitly correlated, frequency-dependent two-body operator which is local in real-space representation. The resulting electron-hole interaction kernel expressed in an energy-restricted subspace of particle-hole excitations is derived using the Lowdin's partitioning theory. Finally, the excitation energies are calculated using an iterative solution of the energy-dependent, generalized pseudoeigenvalue equation. The FD-GSIK method was used to investigate low-lying excited states of a series of silver linear clusters and nanowires. The results from this investigation demonstrate that FD-GSIK is an effective method for investigating electronic excitations and capturing electron-hole correlation in nanomaterials.