On the determination of the minimum on the crossing seam of two potential energy surfaces

An improved gradient-based algorithm is presented for the determination of the minimum energy point on the crossing seam hypersurface between two arbitrary potential energy hypersurfaces. The Hessian matrix is updated employing the gradient information. The method is demonstrated in a study of some representative cases including charge-transfer states of a typical molecular-device molecule (a rigid spiro π – σ – π molecular cation) with, as well as without, an external electric field.