We report the first-principles DFT calculation of the electron-hole Lindhard response function of the (TMTSF)2PF6 Bechgaard salt using the real triclinic low-temperature structure. The Lindhard response is found to change considerably with temperature. Near the 2kF spin density wave (SDW) instability it has the shape of a broad triangular plateau as a result of the multiple nesting associated with the warped quasi-one-dimensional Fermi surface. The evolution of the 2kF broad maximum as well as the effect of pressure and deuteration is calculated and analyzed. The thermal dependence of the electron-hole coherence length deduced from these calculations compares very well with the experimental thermal evolution of the 2kF Bond Order Wave correlation length. The existence of a triangular plateau of maxima in the low-temperature electron-hole Lindhard response of (TMTSF)2PF6 should favor a substantial mixing of q-dependent fluctuations which can have important consequences in understanding the phase diagram of the 2kF SDW ground state, the mechanism of superconductivity and the magneto-transport of this paradigmatic quasi-one-dimensional material. The first-principles DFT Lindhard response provides a very accurate and unbiased approach to the low-temperature instabilities of (TMTSF)2PF6 which can take into account in a simple way 3D effects and subtle structural variations, thus providing a very valuable tool in understanding the remarkable physics of molecular conductors.

中文翻译：

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第一性原理 Lindhard 响应函数揭示(TMTSF) ₂ PF ₆ Bechgaard 盐的费米表面电子空穴不稳定性

我们报告了使用真实三斜低温结构的 (TMTSF)2PF6 Bechgaard 盐的电子-空穴 Lindhard 响应函数的第一性原理 DFT 计算。发现 Lindhard 响应随温度发生显着变化。在 2kF 自旋密度波 (SDW) 不稳定性附近，由于与扭曲的准一维费米表面相关的多重嵌套，它具有宽三角形平台的形状。计算和分析了 2kF 宽最大值的演变以及压力和氘化的影响。从这些计算中推导出的电子-空穴相干长度的热相关性与 2kF 键阶波相关长度的实验热演化非常相配。(TMTSF)2PF6 的低温电子空穴 Lindhard 响应中存在三角形最大值平台应该有利于 q 相关波动的大量混合，这可能对理解 2kF SDW 基态的相图产生重要影响，超导机制和这种范式准一维材料的磁传输。第一性原理 DFT Lindhard 响应为 (TMTSF)2PF6 的低温不稳定性提供了一种非常准确和无偏的方法，可以以简单的方式考虑 3D 效应和细微的结构变化，从而为理解分子导体的非凡物理学。