From 311aaf7df7711ac0ede29b758707742a4cd629af Mon Sep 17 00:00:00 2001 From: chn Date: Sun, 4 May 2025 22:08:02 +0800 Subject: [PATCH] --- test-typst/main.typ | 62 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 51 insertions(+), 11 deletions(-) diff --git a/test-typst/main.typ b/test-typst/main.typ index 5e11641..31dc7a3 100644 --- a/test-typst/main.typ +++ b/test-typst/main.typ @@ -82,18 +82,58 @@ In this paper, we do some things. We do something for the first time. = Results and Discussion -// 拉曼活性的声子模式对应于 Gamma 点附近的声子模式。 -// 根据这些声子模式在拉曼实验中的表现,我们将这些声子分成三个部分。 +== Phonons in Perfect 4H-SiC + +// 拉曼活性的声子模式对应于 Gamma 点附近的声子模式。 +// 根据这些声子模式的极性,我们将这些声子分成两类。 +Raman scattering peeks correspond to phonons located near the $Gamma$ point in reciprocal space. +We classified these phonons into two categories based on their polarities: + (i) negligible-polar phonons (i.e., phonons with no polarity or very weak polarity), + whose dispersion curves are continuous near the Γ point (as shown in @phonon), + and for which the effect of polarity can be ignored in the Raman scattering process; + and (ii) strong-polar phonons, + whose dispersion curves exhibit discontinuity near the Γ point (also shown in @phonon), + where the polarity gives rise to observable effects in the Raman spectra. + +#figure( + image("/画图/声子不连续/整体图.svg", width: 80%), + caption: [Weak- and None-polarized phonons near $Gamma$ point], + placement: none +) + +=== Phonons with Negligible Polarities + +// 我们使用 Gamma 点的声子模式来近似拉曼过程中的非极性声子。 +// 这个近似被广泛使用,并且由于这个原因而被认为是可行的: +// 尽管拉曼过程中起作用的声子并不是那些严格在 Gamma 点的, +// 但这些声子模式的散射谱在 Gamma 附近连续且导数为零,且波矢很小(在本文中大约 0.01 A,只有c轴的大约2%)。 +// 因此,它们的性质与 Gamma 点的声子模式区别不大。 +Phonons at the $Gamma$ point were used + to approximate negligible-polar phonons that participating in Raman processes. +This approximation is widely adopted and justified by the fact that, + although the phonons participating in Raman processes are not these strictly located at the $Gamma$ point, + their dispersion near the $Gamma$ point is continuous with vanishing derivatives, + and their wavevector is very small + (about 0.01 AA in this paper, which corresponds to only 2% of the smallest reciprocal lattice vector of 4H-SiC). + // TODO: 确认这个数值 +Therefore, negligible-polar phonons involved in Raman processes + have nearly indistinguishable properties from those at the $Gamma$ point. + +// 4H-SiC 在 Gamma 有 21 个distinct phonons,其中极性较弱的有 18 个。这些模式对应于点群 $\mathrm{C_{6v}}$ 的 12 个表示($\mathrm{3A_1+4B_1+3E_1+4E_2}$。 +// 对于非极性声子的拉曼散射,我们将使用 Gamma 点的声子模式来近似描述。 +// 这是因为,尽管拉曼实验中,起作用的声子并不严格在 Gamma 点;但这些声子模式的散射谱在 Gamma 附近是连续且导数为零,且起作用的声子离开 Gamma 点的距离也很小(对于 532 nm 的激光,离开 Gamma 点的距离小于 0.01 Å),它们的性质与 Gamma 点的声子模式区别不大。 + + + +// +// +// 不同方向入射/散射光的拉曼实验对应于 Gamma 附近、偏向于不同方向的声子。 +// 其中 $\mathrm{A_1}$、$\mathrm{B_1}$ 为一维表示,对应于无简并的声子;$\mathrm{E_1}$、$\mathrm{E_2}$ 为二维表示,对应于二重简并的声子。 +// 在拉曼实验中,起作用的声子并不严格在 Gamma 点;但大多数声子的色散谱在 Gamma 点连续且导数(斜率)为零,因此大多情况下可以沿用这个分类,少数情况我们稍后会专门讨论。 + + +// 4H-SiC 在 Gamma 点的声子共有 21 个模式,这些模式对应于点群 $\mathrm{C_{6v}}$ 的 14 个表示($\mathrm{3A_1+4B_1+3E_1+4E_2}$,其中 $\mathrm{A_1}$、$\mathrm{B_1}$ 为一维表示,对应于无简并的声子;$\mathrm{E_1}$、$\mathrm{E_2}$ 为二维表示,对应于二重简并的声子)。在拉曼实验中,起作用的声子并不严格在 Gamma 点;但大多数声子的色散谱在 Gamma 点连续且导数(斜率)为零,因此大多情况下可以沿用这个分类,少数情况我们稍后会专门讨论。 -Raman scattering peeks correspond to phonons located near $Gamma$ point in reciprocal space. -We classified these phonons into three categories according to their behavior in Raman scattering: - (1) phonons could not be observed in Raman scattering spectrum, - either because they are Raman inactive or their scattering intensity is too weak; - (2) phonons could be observed in Raman scattering spectrum and with weak or no polarities, - their frequencies were independent of the direction of the incident light; - (3) strong polar phonons, - which were visible in Raman scattering spectrum, - and their frequencies depend on the direction of the incident light. // 我们计算了 4H-SiC 在 A-Gamma 和 Gamma-M 上的声子频率,如图和附录1所示。 // 在拉曼散射中,起作用的模式都是那些非常接近于 Gamma 的模式