Time-dependent hole states in multiconfigurational time-dependent Hartree-Fock approaches: Applications in photoionization of water molecule

By simulating the real-time multi-electron wavefunction with the multiconfigurational time-dependent Hartree-Fock (MCTDHF) approach, we conduct an study of the single-photon ionization process of a body-fixed water molecule ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi mathvariant="normal">H</a:mi> <a:mn>2</a:mn> </a:msub> <a:mi mathvariant="normal">O</a:mi> </a:mrow> </a:math> ) driven by attosecond pulses. To this end, we present a full-dimensional implementation of the MCTDHF method based on one-center expansions, allowing for the simulation of arbitrarily polarized lasers and multicenter polyatomic potentials. With a rigorous definition of the time-dependent hole state (TDHS) using the time-domain generalization of extended Koopmans' theorem, we derive the reduced ion density matrix within the MCTDHF framework, which inherently encodes the total and channel-resolved photoionization cross sections of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:msub> <d:mi mathvariant="normal">H</d:mi> <d:mn>2</d:mn> </d:msub> <d:mi mathvariant="normal">O</d:mi> </d:mrow> </d:math> . The cross sections obtained are benchmarked against existing experimental and theoretical results, validating the TDHS formalism. Furthermore, by adjusting the phase delay and intensity ratio of a pair of orthogonally polarized attosecond pulses, we explore the ultrafast control of attosecond coherence between electronic states of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:msub> <g:mi mathvariant="normal">H</g:mi> <g:mn>2</g:mn> </g:msub> <g:msup> <g:mi mathvariant="normal">O</g:mi> <g:mo>+</g:mo> </g:msup> </g:mrow> </g:math> .