-If we want to calculate the IRC trajectory of a structure, it is possible to do it with GRRM with the keyword IRC, and it will give you the IRC path in both directions, the forward and the backwards direction to the Gradient Vector. Now, if you want only one of the directions of the IRC path, you could use the keyword Meta-IRC to compute ONLY the forward path. is there a way to compute ONLY the backward path? I am assuming the forward and backward concept from Gaussian, in which they refer to the direction of the gradient Vector, which means that sometimes the Product path can be in the Reverse direction and not the Forward direction.
The meta-IRC is the steepest descent path in the mass-weighted coordinates. Therefore, it leads toward the inverse direction of the gradient vector (even when the norm of gradient vector is very small).