<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="">Dear all,</div>After extensively testing the recently implemented forces for U_projection_type = 'ortho-atomic’, I have come across several cases where the geometry optimizations would fail: the energy would fluctuate without convergence using BFGS, and even damped dynamics would frequently not converge. Such a behavior usually points to a problem with the forces, which are either not exact or noisy.<div class=""><br class=""></div><div class="">Based on this observation, I decided to perform a routine test: I compute the integral of the forces times displacement along a path in configurational space, and compare it with the energy difference between the initial and final point. If the forces are exact derivatives of the energy, the path integral must be identical to the energy difference (up to machine precision if the step size of the path integral goes to zero). The method is described in sec 3.3, <a href="https://doi.org/10.1016/j.cpc.2020.107415" class="">https://doi.org/10.1016/j.cpc.2020.107415</a>, see also the attachment of the relevant section. </div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""></div></body></html>