We discuss the first theory for the depinning of low dimensional, incommensurate, charge density waves (CDWs) in the strong electron-phonon (e-p) regime. Arguing that most real CDWs systems invariably develop a gigantic dielectric constant (GDC) at very low frequencies, we propose an electromechanical mechanism which is based on a local field effect. At zero electric field and large enough e-p coupling the structures are naturally pinned by the lattice due to its discreteness, and develop modulation functions which are characterized by discontinuities. When the electric field is turned on, we show that it exists a finite threshold value for the electric field above which the discontinuities of the modulation functions vanish due to CDW deformation. The CDW is then free to move. The signature of this pinning/depinning transition as a function of the increasing electric field can be directly observed in the phonon spectrum by using inelastic neutrons or X-rays experiments.
Modulating Peierls distortion of 1T_prime MoS2 via charge doping: a new charge density wave phase, reversible phase transition, and excellent electromechanical properties
过渡金属二硫属化合物（TMD）的1 T ′相是一种低对称性的电荷密度波（CDW）相，可以看作是高对称性1 T相的周期性畸变结构（Peierls畸变）。本文利用密度泛函理论（DFT）计算，研究了正电荷（空穴）注入对MoS 2 1T_prime的Peierls畸变的调制作用.当空穴掺杂浓度为~ 0.10h+/atom时，发现了一种新的稳定的CDW相，命名为1Tt_prime。空穴的充放电可以引起MoS 2在1 T、1T_prime和1Tt_prime三相之间的可逆相变。这种可逆的相变导致优异的机电性能，包括高达-5.8%的应变输出，具有小的磁滞回线、多阶超弹性和多形状记忆效应，这在纳米级的有源机电器件设计中是有价值的。对空穴掺杂下电子结构的变化进行了深入的分析，以理解新的CDW相和观察到的相变。使用电荷掺杂来调制二维材料中的Peierls畸变可以作为纳米活性物质设计的一般概念。
利用密度泛函理论研究了1H、1 T和1 T $^\prime$结构的二维MoS $_2$单分子膜的机电性质随电荷掺杂的变化.我们发现在1H和1 T结构的各向同性的弹性模量，而1 T $^\prime$结构表现出各向异性的弹性模量。此外，1 T结构显示具有负泊松比，而1H和1 T $^\prime$的泊松比为正。通过电荷掺杂，单层MoS $_2$显示出每次循环的可逆应变和功密度分别为-0.68%至2.67%和4.4至36.9 MJ/m $^3$，使它们适合于在机电致动器中的应用。在这项工作中产生的应力也进行了检查，我们发现，1 T和1 T $^\prime$ MoS $_2$单分子膜相对有更好的性能比1H MoS $_2$单分子膜。我们认为，这种优异的机电性能源于导电性的金属1 T和半金属1 T $^\prime$结构的高杨氏模量约$150-200$ GPa。
Space charge dynamics in solid electrolytes with steric effect and Vegard stresses: resistive switching and ferroelectric-like hysteresis of electromechanical response
Compact and explicit physical model for lateral metal-oxide-semiconductor field-effect transistor with nanoelectromechanical system based resonant gate
Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3
