We give presentations of the asymptotic expansions of the Kashaev invariant of the knots with 6 crossings. In particular, we show the volume conjecture for these knots, which states that the leading terms of the expansions present the hyperbolic volume and the Chern-Simons invariant of the complements of the knots. As higher coefficients of the expansions, we obtain a new series of invariants of these knots.A non-trivial part of the proof is to apply the saddle point method to calculate the asymptotic expansion of an integral which presents the Kashaev invariant. A key step of this part is to give a concrete homotopy of the (real 3-dimensional) domain of the integral in C 3 in such a way that the boundary of the domain always stays in a certain domain in C 3 given by the potential function of the hyperbolic structure. Classification (2010). Primary: 57M27. Secondary: 57M25, 57M50.
Mathematics Subject(3) directly. We give such a homotopy concretely in Sections 3.5, 4.5, 5.5 for the 6 1 , 6 2 , 6 3 knots respectively. This part of the proof is quite non-trivial; in fact, we note that we can not make such a homotopy for the 7 2 knot as shown in [21].By the method of this paper, the asymptotic behavior of the Kashaev invariant is discussed for the hyperbolic knots with 7 crossings in [21] and for some hyperbolic knots with 8 crossings in [24].