Dear all <img alt="12.PNG" width="533px" height="277px" src="cid:b458ce10-7603-4d0f-acca-4e55da571d6f" /> I'm working with a NASICON-type structure(Na3Zr2Si2PO12), and I need some help regarding a cation substitution and charge compensation strategy in CP2K. In my case, I intend to replace Zr⁴⁺ ions with Mg²⁺ ions in the structure. As you can see, this substitution introduces a +2 charge deficit per Mg²⁺ ion, and I would like to know the best way to compensate for this charge imbalance — possibly by adding Na⁺ ions. My main questions are: <ol><li> How can I properly introduce additional Na⁺ ions in CP2K to compensate for the charge imbalance caused by Mg²⁺ replacing Zr⁴⁺? Is there a recommended way to control total charge or to specify interstitial Na sites? </li><li> How can I determine the most favorable or stable positions for the substituted Mg²⁺ ions and the compensating Na⁺ ions in the NASICON structure? Should I use energy-based relaxation, MD simulations, or site-specific energy comparisons? Is there a common practice for this type of site analysis in CP2K? </li></ol> I would appreciate any guidance, examples, or suggestions regarding how to set this up correctly — especially in terms of modeling charge neutrality and realistic ion placement. -- 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/826dcf4c-4705-43a2-bc88-076760ad0ac0n%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/826dcf4c-4705-43a2-bc88-076760ad0ac0n%40googlegroups.com</a>.