Temperature effects for vibrational relaxation of hydrogen adsorbed on Si(100): a stochastic multiconfigurational time-dependent Hartree (MCTDH) study
Temperature effects for vibrational relaxation of hydrogen adsorbed on Si(100): a stochastic multiconfigurational time-dependent Hartree (MCTDH) study
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Si(100) 上吸附的氢振动弛豫的温度效应：随机多构型时间相关 Hartree (MCTDH) 研究
DOI：
10.1007/s00214-009-0721-y
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发表时间：
2010
影响因子：
1.7
通讯作者：
P. Saalfrank
中科院分区：
文献类型：
--
作者：
F. Lüder;M. Nest;P. Saalfrank
使用先前开发的用于吸附在Si（100）表面上的H原子的振动弛豫的系统浴模型哈密顿量（Andrianov和Saalfrank in J Chem Phys 124：034710，2006），非微扰地研究了温度对激发的吸附物振动的弛豫的影响。特别是，Si-Si-H弯曲模式，其中的弛豫时间在皮秒的顺序已被理论预测，被认为是。此外，红外激光脉冲的激发明确建模。为此，考虑了一个组合系统浴薛定谔方程，其中描述振动H原子的非谐系统非线性耦合到一组代表固体声子浴的谐振子。对于时间演化，多组态时间相关的Hartree（MCTDH）方法一起使用的随机方法来采样热初始条件。与微扰方法（黄金法则）相反，发现弯曲模式松弛得越慢，表面越热。这个“难题”，这似乎也与测量的H：Si（100）的差异，可能的原因进行了讨论。
Using a previously developed system–bath model Hamiltonian for the vibrational relaxation of H atoms adsorbed on a Si(100) surface (Andrianov and Saalfrank in J Chem Phys 124:034710, 2006), temperature effects on the relaxation of excited adsorbate vibrations are studied non-perturbatively. In particular, the Si–Si–H bending mode, for which relaxation times in the order of picoseconds have been predicted theoretically, is considered. Also, the excitation by infrared laser pulses is explicitly modelled. To do so, a combined system–bath Schrödinger equation is considered, in which an anharmonic system describing the vibrating H atom is coupled non-linearly to a set of harmonic oscillators which represent the phonon bath of the solid. For the time evolution, the multiconfigurational time-dependent Hartree (MCTDH) method is used together with a stochastic approach to sample thermal initial conditions. In contrast to perturbative approaches (Golden Rule), it is found that the bending mode relaxes the slower, the hotter the surface is. Possible reasons for this “puzzle”, which also seems at variance with measurements for H:Si(100), are discussed.