(ΔE2ϕ0)Eϕ0/2=−2πa0L3[1+c1a0L+c2a20L2] c1=−2.837297 and c2=6.375183
χ2/d.o.f.=0.92944P[0]=−0.567365±(0.011) {C=(0.000112)}