Mode-selective excitation of hydrogen atoms on a Si surface: Non-Markovian and Markovian treatment of infrared laser driven dissipative quantum dynamics

Abstract

Mode-selective excitation of adsorbates by shaped infrared laser pulses is investigated here theoretically, for the example of a H atom on a hydrogen-covered Si͑100͒-2 ϫ 1 surface. The mode-selective excitation is perturbed by the intermode coupling within the system ͑bending and stretching modes͒ and by system-bath coupling to substrate phonons. Using a force-field based model, vibration-phonon coupling was found and predicted to lead to vibrational relaxation of the H-Si stretching mode on a ns timescale, and of the Si-Si-H bending mode on a ps timescale ͓I. Andrianov and P. Saalfrank, J. Chem. Phys. 124, 034710 ͑2006͔͒. To address the question as to whether in such a dissipative situation mode-selective control of adsorbate vibrational dynamics is still possible, a system-bath ansatz is used to derive an open-system density matrix theory in which the H vibrations are driven either by sin 2 , or by freely optimized infrared ps laser pulses. Both for the Si-H stretching and Si-Si-H bending vibrations mode-selective excitation is predicted to be possible. It is also found that the Markov approximation works well in most of the applications, and that simple sin 2 are nearly as effective as pulses which were freely optimized by optimal control theory.

Reduced and Exact Quantum Dynamics of the Vibrational Relaxation of a Molecular System Interacting with a Finite-Dimensional Bath

“…There are, however, also marked differences to the Lindblad model. First of all, the decay is nonexponential, with a slope d P 1 /d t = 0 at t = 0, which is a clear signature of nonmarkovian behavior . Second, at times longer than 500 fs, when P 1 = ρ 11 = 0 and P 0 = ρ 00 = 1, the excited state population rises again, reaching ρ 11 = 1 after t = 1000 fs.…”

Quantendynamik komplexer Systeme

“…• State‐of‐the‐art‐Anwendungen zur Simulation von Spektren und Energietransfer in Lichtsammelkomplexen der Photosynthese, 14,18 Dynamik von Wasserstoffbrückenbindungen6) (Abbildung 3) und lasergetriebener Schwingungsdynamik von Adsorbaten an Oberflächen 19…”

A novel system-bath Hamiltonian for vibration-phonon coupling: Formulation, and application to the relaxation of Si–H and Si–D bending modes of H/D:Si(100)-(2 × 1)

“…The most rigorous way is to solve a multi-dimensional, time-dependent Schrödinger equation of system-bath form, using a discretized bath and efficient methods such as Multi-Configurational Time-Dependent Hartree (MCTDH) [13,14], Multi-Layer MCTDH (ML-MCTDH) [15][16][17], surrogate Hamiltonian methods [18] or other, more approximate schemes such as the Time-Dependent Self-Consistent Field (TDSCF) method [19,20]. An alternative route is via open-system theory, by solving a Liouville-von Neumann equation for the system reduced density matrix (RDM) instead [12,21,22]. When memory effects are neglected this results in Markovian variants such as Redfield theory [23], or the Lindblad dynamical semigroup [7,12,25,24].…”