In contrast, the simplicity and accuracy of the TDQT approach stems from its use of fixed, structured grids in C space, that never change over time. This fortuitous state of affairs is ultimately due to the trajectory-based reformulation, and its replacement of x with C as the requisite "spatial" coordinate-a change also allows for much more natural comparison and integration with classical theories. As a result, the node problem does not lead to a breakdown of the simulation, quasi-nodes inducing a much milder under-sampling problem in our case, rather than a fatal numerical blow up of errors as in standard QTM approaches.