at low photon energies, while suppresses bunched conductivity. Detailed analysis when AB and AA stackings are mixed in an $N$-layer graphene deserves a further study.

The results for small $N$ below 1500 are shown in the right panel of Fig. \[fig:Ref\]. The curves obtained from the two conductivities show that similar peak structures originating from an interlayer electronic interaction appear in the reflectance of an $N$-layer graphene at any $N$. Below the peak, the layered conductivity underestimates reflectance compared with the bunched conductivity.

Hanfland [*et al.*]{} observed that a peak energy position in reflectance of natural graphite increased with increasing pressure. [@Hanfland1989a] The observations can be explained as an enhancement of $\gamma_1$, due to the pressure induced contraction of $d$. They also observed that the peak is split into two peaks (denoted by $A_1$ and $A_2$). The splitting was also observed by means of thermoreflectance measurements at atmospheric pressure. [@Bellodi1975] We attribute the splitting to a bond alternation along the $c$-axis. In other words, when interlayer distance $d$ is not exactly uniform but is locally modulated by a certain lattice distortion like a polyacetylene, [@Su1980; @Heeger1988] an asymmetry between the magnitudes of the two extremal mass ($m_1$ and $m_N$) may 