论文标题
时间依赖性自我一致的谐波近似：Anharmonic核量子动力学和时间相关函数
Time-Dependent Self Consistent Harmonic Approximation: Anharmonic nuclear quantum dynamics and time correlation functions
论文作者
论文摘要
大多数具有极大兴趣的物质特性与核动力学直接相关，例如离子热导率，拉曼/IR振动光谱，非弹性X射线和中子散射。能够从第一原则中计算这些特性的理论，这些理论涉及核能景观中可以在具有数百个原子的系统中实施的非谐波和量子波动。在这里，我们得出了在有限温度下晶格振动的量子时间演变的近似理论。该理论介绍了自洽谐波近似（SCHA）中的时间动态，并与静态情况相同的计算成本共享。它是非经验的，因为纯状态根据狄拉克最小动作原理的发展，而热合奏的动力学也可以保守能量和熵。静态SCHA被恢复为动力学方程的固定解。我们在静态SCHA解决方案周围应用扰动理论，并得出算法来计算有效的量子动态响应函数。多亏了这种新算法，我们就可以访问任何一般外部时间依赖性扰动的响应函数，从而实现了声子光谱的模拟，而无需遵循核电位或经验方法的任何扰动膨胀。我们以96个原子为96个原子的高压氢第三期的IR和拉曼光谱进行了基准测试算法。我们的工作还探讨了动态核运动的非线性状态，提供了一个范式，以模拟与泵探测光谱或涉及光原子的化学反应一样，与强度或多个探针相互作用，作为生物分子中的质子转移
Most material properties of great physical interest are directly related to nuclear dynamics, e.g. the ionic thermal conductivity, Raman/IR vibrational spectra, inelastic X-ray, and Neutron scattering. A theory able to compute from first principles these properties, accounting for the anharmonicity and quantum fluctuations in the nuclear energy landscape that can be implemented in systems with hundreds of atoms is missing. Here, we derive an approximate theory for the quantum time evolution of lattice vibrations at finite temperature. This theory introduces the time dynamics in the Self-Consistent Harmonic Approximation (SCHA) and shares with the static case the same computational cost. It is nonempirical, as pure states evolve according to the Dirac least action principle and the dynamics of the thermal ensemble conserves both energy and entropy. The static SCHA is recovered as a stationary solution of the dynamical equations. We apply perturbation theory around the static SCHA solution and derive an algorithm to compute efficiently quantum dynamical response functions. Thanks to this new algorithm, we have access to the response function of any general external time-dependent perturbation, enabling the simulation of phonon spectra without following any perturbative expansion of the nuclear potential or empirical methods. We benchmark the algorithm on the IR and Raman spectroscopy of high-pressure hydrogen phase III, with a simulation cell of 96 atoms. Our work also explores the nonlinear regime of the dynamical nuclear motion, providing a paradigm to simulate the interaction with intense or multiple probes, as in pump-probe spectroscopy, or chemical reactions involving light atoms, as the proton transfer in biomolecules
