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石墨烯等离激元在红外-太赫兹波段具有高度局域化和动态可调性，但其精准调控机制仍需深入探索。本研究基于国产第一性原理计算软件ABACUS，采用线性响应含时密度泛函理论方法，结合截断库仑势消除层间耦合效应，系统研究了石墨烯狄拉克等离激元的三类调控机制。研究结果表明，无论采用何种调控手段，石墨烯狄拉克等离激元的色散关系均呈现出典型的双区域特征：在长波区域，其色散关系遵循√q的形式；而在短波区域，则逐渐过渡为准线性行为。此外，随着载流子浓度的增加，等离激元的激发能量呈现系统性增强，并遵循ω∝n1/4的标度律；施加双轴应变时，等离激元激发能量随晶格常数的增大而线性降低；引入六方氮化硼（hBN）作为基底时，对原始结果影响较小，仅导致整体能量发生轻微红移。进一步地，研究深入揭示了上述三种调控机制的物理起源。这些结果为基于石墨烯/hBN异质结构的高性能动态光电器件设计提供了坚实的理论支撑。
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关键词:
- 第一性原理计算 /
- 石墨烯 /
- 线性响应含时密度泛函理论 /
- 狄拉克等离激元
Graphene Dirac plasmons, which are collective oscillations of charge carriers behaving as massless Dirac fermions, have emerged as a transformative platform for nanophotonics due to their exceptional capability for deep subwavelength light confinement in the infrared to terahertz spectral regions and their unique dynamic tunability. While external controls such as electrostatic doping, mechanical strain, and substrate engineering are empirically known to modulate plasmonic responses, a comprehensive and quantitative theoretical framework from first principles is essential to decipher the distinct effciency and fundamental mechanisms of each tuning strategy. To address this, we present a systematic first-principles investigation into three primary modulation pathways-carrier density, biaxial strain, and substrate integration-using linear-response time-dependent density functional theory within the random-phase approximation (LR-TDDFT-RPA) as implemented in the computational code ABACUS. A truncated Coulomb potential was incorporated to accurately model the isolated two-dimensional system, while structural and electronic properties were computed using the PBE functional with SG15 norm-conserving pseudopoten- tials and van der Waals corrections for heterostructures. Our findings reveal that modulating carrier concentration shifts the plasmon dispersion following the characteristic ω∝ n1/4 scaling, enabling a wide tuning range from 0.45 eV to 1.38 eV at the Landau damping threshold-a 207% change for carrier densities from 0.005 to 0.1 electrons per unit cell, albeit with diminishing effciency at higher concentrations due to the sublinear nature of the scaling law. Biaxial strain linearly alters the plasmon energy by modifying the Fermi velocity (vF ) near the Dirac point, yielding a 30.4% tuning range (0.78-1.12 eV) under ±10% strain. Introducing an hBN substrate induces a small band gap (∼ 43 meV) and causes a general redshift in plasmon energy due to band renormalization, while remarkably preserving the linear straintuning capability with a 30.1% energy range (0.72-1.03 eV) in the heterostructure, demonstrating robust compatibility between strain engineering and substrate integration. These results quantitatively elucidate the distinct physical mechanisms-Fermi level shifting, Fermi velocity modification, and substrate-induced symmetry breaking and hybridization-underpinning each strategy, thereby providing a solid theoretical foundation for the design of dynamically tunable optoelectronic devices based on graphene and its van der Waals heterostructures.-
Keywords:
- First-principles calculations /
- Graphene /
- Linear-response time-dependent density functional theory (LR-TDDFT) /
- Dirac plasmons
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