论文标题
旋转双层石墨烯的Moiré尺度连续模型的简单推导
A simple derivation of moiré-scale continuous models for twisted bilayer graphene
论文作者
论文摘要
我们从密度功能理论中提供了扭曲的双层石墨烯（TBG）的简化模型的形式推导。我们的推导基于TBG Kohn-Sham Hamiltonian和渐近极限技术的变异近似。与其他方法相反，它不需要引入中间紧密结合模型。所谓的模型类似于Bistritzer-Macdonald（BM）模型的模型，但包含其他术语。可以从单层石墨烯和带有不同堆叠的单层双层石墨烯上的Kohn-Sham计算中轻松计算其参数。它尤其允许估计参数$ w _ {\ rm aa} $和$ w _ {\ rm ab} $的bm模型的$ w _ {\ rm ab} $。所得的数值值，即$ w _ {\ rm aa} = w _ {\ rm ab} \ simeq 126 $ MEV，用于实验夹层平均值均与经验值$ W _ {\ rm aa} = w _ {\ rm aa} = w _ {\ rm ab} = 110 $ mev cover fac for经验值$ w _ {\ rm aa} = w _ {\ rm aa} = w _我们还表明，如果将BM参数设置为$ W _ {\ rm aa} = w _ {\ rm ab} \ simeq 126 $ MEV，则BM模型是我们还原模型的准确近似。
We provide a formal derivation of a reduced model for twisted bilayer graphene (TBG) from Density Functional Theory. Our derivation is based on a variational approximation of the TBG Kohn-Sham Hamiltonian and asymptotic limit techniques. In contrast with other approaches, it does not require the introduction of an intermediate tight-binding model. The so-obtained model is similar to that of the Bistritzer-MacDonald (BM) model but contains additional terms. Its parameters can be easily computed from Kohn-Sham calculations on single-layer graphene and untwisted bilayer graphene with different stackings. It allows one in particular to estimate the parameters $w_{\rm AA}$ and $w_{\rm AB}$ of the BM model from first-principles. The resulting numerical values, namely $w_{\rm AA}= w_{\rm AB} \simeq 126$ meV for the experimental interlayer mean distance are in good agreement with the empirical values $w_{\rm AA}= w_{\rm AB}=110$ meV obtained by fitting to experimental data. We also show that if the BM parameters are set to $w_{\rm AA}= w_{\rm AB} \simeq 126$ meV, the BM model is an accurate approximation of our reduced model.
