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arXiv physics/9907050physics.chem-phphysics.atm-clus
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含核动力学的电子-分子散射的动力学格林函数和精确光学势

The dynamical Green's function and an exact optical potential for electron-molecule scattering including nuclear dynamics

Joachim Brand, Lorenz S. Cederbaum, Hans-Dieter Meyer

摘要:

我们推导出一个严格的光学势电子分子散射包括核动力学的影响,通过扩展常见的多体格林函数方法的光学势超出固定的核限制的分子目标。我们的形式主义对待抛射电子和核运动的目标分子在同一个立足点,从而严格的动态光学势帐户的散射目标的复杂的多体性质。目前的工作的一个中心结果是,共同的固定核光学势是一个有效的绝热近似的动态光学势,即使当弹丸和核运动(非绝热)耦合,只要散射能量远低于电子激发阈值的目标。对于极低的弹丸速度,然而,当截面是最敏感的散射势,我们预计的影响,核动力学的光学势成为相关的。对于这些情况下,一个系统的方法来提高绝热近似的动态光学势,产生非本地运营商相对于核坐标。

英文摘要:

We derive a rigorous optical potential for electron-molecule scattering including the effects of nuclear dynamics by extending the common many-body Green's function approach to optical potentials beyond the fixed-nuclei limit for molecular targets. Our formalism treats the projectile electron and the nuclear motion of the target molecule on the same footing whereby the dynamical optical potential rigorously accounts for the complex many-body nature of the scattering target. One central result of the present work is that the common fixed-nuclei optical potential is a valid adiabatic approximation to the dynamical optical potential even when projectile and nuclear motion are (nonadiabatically) coupled as long as the scattering energy is well below the electronic excitation thresholds of the target. For extremely low projectile velocities, however, when the cross sections are most sensitive to the scattering potential, we expect the influences of the nuclear dynamics on the optical potential to become relevant. For these cases, a systematic way to improve the adiabatic approximation to the dynamical optical potential is presented that yields non-local operators with respect to the nuclear coordinates.

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