def yield_pair_hessians(self, index1, index2):
A = self.As[index1, index2]<EOL>B = self.Bs[index1, index2]<EOL>distance = self.distances[index1, index2]<EOL>yield B*B*A*np.exp(-B*distance), np.zeros((<NUM_LIT:3>, <NUM_LIT:3>))<EOL>
Yields pairs ((s''(r_ij), grad_i (x) grad_i v(bar{r}_ij))