The Berry phase and curvature are studied for the Dirac nodal line semimetal of single-component molecular conductor [Pd(dddt)$_2$]. Using two-band model on the basis of a tight-binding model, it is shown that the Berry curvature, $\bm{ B}(\bm{ k})$, exists along a loop of the nodal line, on which the Berry phase is obtained from surface integral of $\bm{ B}(\bm{ k})$. The Berry phase, which is called Zak phase, is also calculated from one-dimensional integral of the Berry connection along a line between two equivalent points of boundaries of Brillouin zone. The possible experiment is discussed in terms of the Berry phase.
Categories: cond-mat.mes-hall cond-mat.mtrl-sci