Second-order Langevin equation in quantized Hamilton dynamics

作者：Heatwole Eric M; Prezhdo Oleg V^*

来源：Journal of the Physical Society of Japan, 2008, 77(4): 044001.

DOI：10.1143/JPSJ.77.044001

• semiclassical dynamics
• closure
• Langevin equation
• canonical ensemble
• fluctuation-dissipation theorem
• Gaussian

We derive a semi-classical Langevin equation that, in conjuction with a quantum fluctuation-dissipation theorem, can be used to run canonical dynamics and to determine thermal averages in the second-order quantized Hamilton dynamics (QHD-2). In contrast to our earlier work [J. Chem. Phys. 122 (2005) 234109], the bath is no longer treated classically, and the friction is represented at the second-order. As a result, the quantum fluctuation variables are kept close to their optimal values, similarly to the recently developed phase-space canonical averaging for QHD-2 [J. Chem. Phys. 126 (2007) 204108]. The theory is exact for the quantum harmonic oscillator and the free particle, and gives good agreement with the quantum answer for a variety of quartic potentials.

• 出版日期2008-4