Calculate the rotational contribution to the Helmholtz potential per molecule by evaluating the first two terms of equation 16.29 explicitly and by integrating over the remaining terms. For this purpose note that the leading terms in the Euler-McLaurin sum formula are
j=0∑∞f(j)≈∫0∞f(θ)dθ+21f(0)−121f′(0)+⋯
where f′ denotes the derivative of f(θ).