Electron-positron interactions have been utilized in various fields of science. Here we develop time-dependent multi-component density functional theory to study the coupled electron-positron dynamics from first principles. We prove that there are coupled time-dependent single-particle equations that can provide the electron and positron density dynamics, and derive the formally exact expression for their effective potentials. Introducing the adiabatic local density approximation to time-dependent electron-positron correlation, we apply the theory to the dynamics of a positronic lithium hydride molecule under a laser field. We demonstrate the significance of electron-positron dynamical correlation by revealing the complex positron detachment mechanism and the suppression of electronic resonant excitation by the screening effect of the positron.When a low-energy positron beam is directed to a material, the incident positron diffuses inside the bulk and is finally annihilated with atomic electrons and γ rays are emitted [1]. Analysis of these γ rays provides various information related with the surface structures, lattice defects, and electronic structures of the material [1][2][3]. The analysis of positron-annihilation γ rays has been utilized in many applications, such as positron annihilation spectroscopy [4] and positron emission tomography [5]. The positron-material interaction plays a key role in these experiments [6]. The interaction between positron and atom or molecule has also been widely studied to better understand how positrons interact with atomic electrons and are bound to them [7,8]. An experiment that measured positron-atom binding energies through the study of positron-atom recombination under a laser field was recently reported [9].Theoretical approaches to study these positron physics have been extensively developed [10]. Among them, two-component density functional theory (2C-DFT) [2,11], which is an extension of DFT [12] to the coupled electron-positron system, has been a powerful first-principles tool to calculate the ground-state electron and positron densities and their properties. 2C-DFT has been successfully applied to studies of positron interaction with atoms, solids and surfaces to determine the electron-positron momentum distributions [13], positron annihilation lifetimes [14], and positron binding energies [15], to name a few. Another powerful method is the wavefunction-based approach, such as the multi-component molecular orbital method [16] and quantum Monte Carlo method [17,18], which have also revealed much positron physics with high accuracy. However, the dynamical interaction mechanism between positrons and electrons, especially under a laser field [7-9], has not yet been clarified, because there has been no first-principles method that can simulate the correlated dynamics of positrons and electrons for realistic systems.In this study, we develop time-dependent multicomponent density functional theory (TDMCDFT) [19,20] toward an understanding of the mechanism of coupled electro...
