Precision calculations of high-order harmonic generation of H$_{2}^{+}$: time-dependent non-Hermitian Floquet approach

Precision 3D calculations of high-order harmonic generation (HHG) rates of H$_{2}^{+}$ in intense 532 nm laser fields are performed [1] using the \textit{time-dependent non-Hermitian Floquet} approach recently developed [2]. The procedure involves the extension of the \textit{complex-scaling generalized pseudospectral} method for non-uniform spatial discretization of the Hamiltonian and non-Hermitian time propagation of the time-evolution operator. The HHG rates are computed at the equilibrium internuclear separation ($R = 2.0$ a.u.) and several laser intensities, as well as at the laser intensity $5\times 10^{13}$ W/cm$^{2}$ and various internuclear distances in the range between 3.0 and 17.5 a.u. At some internuclear separations $R$, the HHG productions are strongly enhanced and this phenomenon can be attributed to the resonantly enhanced multiphoton ionization at these $R$. \\ \noindent [1] D.~A.~Telnov and S.~I.~Chu, Phys.~Rev.~A \textbf{71}, 013408 (2005).\\ \noindent [2] D.~A.~Telnov and S.~I.~Chu, J.~Phys.~B \textbf{37}, 1489 (2004).