<span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">Hi Quentin, <span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">Thank you for your thoughtful suggestions. I have implemented your recommendations, all of which have certainly improved the computational efficiency. However, I am still encountering persistent SCF convergence failures at the moment of collision with the external potential, regardless of whether diffuse functions are included in the basis set (I tested aug-cc-pVTZ, cc-pVTZ, def2-TZVPPD, and def2-TZVPP). <span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">To circumvent the challenges posed by the external harmonic potential, I created a QM/MM workflow that models the Au surface classically. Unfortunately, similar SCF convergence issues arise when the EMI-BF4 neutral collides with the Au surface in the QM/MM framework. I was curious if there are any gaps in my current QM/MM framework that may cause this lack of SCF convergence? Additionally, I was curious if you or the community could recommend accurate sources or standard references for Lennard-Jones (LJ) pair potentials between the relevant QM atoms (N, C, H, B, and F) and Au atoms? Currently, I am using Lorentz-Berthelot combing rules from the <a href="https://openkim.org/id/MO_959249795837_003"><span style="font-size: 10.5pt; font-family: Roboto, sans-serif; background-color: transparent; font-style: italic; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">Efficient 'universal' shifted Lennard-Jones model for all KIM API supported species developed by Elliott and Akerson (2015) v003</a><span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-style: italic; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">. <span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">I have attached the relevant input file for your review in .zip format. Thank you again for your valuable advice, and I look forward to any insights you or others in the CP2K community might have. <span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">All my best,<span style="font-size: 10.5pt; font-family: Roboto, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alternates: normal; font-variant-position: normal; font-variant-emoji: normal; vertical-align: baseline; white-space-collapse: preserve;">Nick -- You received this message because you are subscribed to the Google Groups "cp2k" group. To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>. To view this discussion visit <a href="https://groups.google.com/d/msgid/cp2k/b271baf7-ccdc-4477-92af-fdaaa61d0312n%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/b271baf7-ccdc-4477-92af-fdaaa61d0312n%40googlegroups.com</a>.