The sampling is also relevant to the consequent nuclear simulation methods. With (quasi-)classical dynamics, some regions can't be accessed and configurations in these classically forbidden regions are not sampled. If quantum mechanics approach is used for the simulation, generally the sampling configurations are in wider regions. This is due to that the action of the potential energy operator onto the wave packet 134 is calculated by the discrete variable representation (DVR) 135 based on some specified coordinates. Therefore, additional points, often with high energies and distorted configurations, should be added to make the potential matrix meaningful. Or else, lacking points in these classically forbidden regions may result "holes" 137 in the PESs and affect the quantum dynamics.