-a^{a0}_{c3} b^{c0}_{v0} c^{c2,c3}_{c1,a1} eta1^{a1}_{a0} a+(c1) a+(v0) a-(c2) a-(c0)
-1/2 a^{a0}_{c3} b^{c3}_{v0} c^{c1,c2}_{c0,a1} eta1^{a1}_{a0} a+(c0) a+(v0) a-(c2) a-(c1)