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arXiv 1006.2264cond-mat.mtrl-sci
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金属表面非绝热分子动力学中的记忆效应

Memory effects in non-adiabatic molecular dynamics at metal surfaces

Thomas Olsen, Jakob Schiøtz

摘要:

我们研究了时间相关性在描述金属表面非绝热动力学的朗之万方程中的作用。对于谐振子,朗之万方程精确地保持了量子动力学,并且证明了为了保持谐振子的基态能量,需要有记忆效应。然后,我们比较了结果的朗之万动力学的调和势与微扰主方程的方法,并表明朗之万方程给出了更好的描述在非微扰范围内的高温和大摩擦。与主方程不同,这种方法很容易扩展到非谐势。利用密度泛函理论计算了N $_2$从Ru(0001)上缔合解吸的典型Langevin轨道,发现记忆效应降低了能量耗散.最后,我们提出了一个在密度泛函理论中计算时间关联函数和动力学摩擦的从头计算方法。

英文摘要:

We study the effect of temporal correlation in a Langevin equation describing non-adiabatic dynamics at metal surfaces. For a harmonic oscillator the Langevin equation preserves the quantum dynamics exactly and it is demonstrated that memory effects are needed in order to conserve the ground state energy of the oscillator. We then compare the result of Langevin dynamics in a harmonic potential with a perturbative master equation approach and show that the Langevin equation gives a better description in the non-perturbative range of high temperatures and large friction. Unlike the master equation, this approach is readily extended to anharmonic potentials. Using density functional theory we calculate representative Langevin trajectories for associative desorption of N$_2$ from Ru(0001) and find that memory effects lowers the dissipation of energy. Finally, we propose an ab-initio scheme to calculate the temporal correlation function and dynamical friction within density functional theory.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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