The trial wave function o: dt ov,=0 φ=∑=1aVk dτ E=Jdψ/dφ=∑2aPE/2 Ja, E alal EThe trial wave function f: dt f * y1 = 0 f = k=1 ak yk dt f * y1 = |a1 | 2 = 0 Ef = dt f *Hf / dt f *f = k=2|ak | 2Ek / k=2|ak | 2 > k=2|ak | 2E2 / k=2|ak | 2 = E2