Time-Dependent Multicomponent Density Functional Theory for Coupled Electron-Positron Dynamics

Electron-positron interactions have been utilized in various fields of science. Here we develop time-dependent multicomponent 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 the coupling between electronic and positronic motion by revealing the complex positron detachment mechanism and the suppression of electronic resonant excitation by the screening effect of the positron.

Figure 1

(a) Snapshots of $n^{-}(x,t)$ (black) and $n^{+}(x,t)$ (red) at $t=0$ (dotted) and $t=4.36\mathrm{fs}$ (solid) in the dynamics of $e^{+}$-LiH under a laser field ($\omega =1.5\mathrm{eV}$), and (b) corresponding $v_{\mathrm{KS}}^{\mp }(x,y_c,z_c,t)$. The inset shows the isosurfaces of the ground-state densities (see text).

Figure 2

(a) Time evolution of positron detachment probability for three different laser fields, and (b) corresponding $E(t)$.

Figure 3

(a) Time-dependent dipole moment of LiH $d_x^{-}(t)$ of $e^{+}$-LiH (red) and LiH (black) under the laser field ($\omega =3.0\mathrm{eV}$), and (b) corresponding $E(t)$.