<div dir="ltr">Hi Matthias, Thank you for the response. I had overlooked the basis sets in the BASIS_MOLOPT_UCL file. Unfortunately these basis sets are unlikely to be suitable for my purpose which (as i should have mentioned in my original post) is to use the basis set to build a tight binding model (which has different requirements to KS-DFT basis sets, e.g. shorter ranged orbitals are preferred). The reason I'm doing cp2k calculations is essentially to estimate the errors that arise from using this basis set (compared to a more complete one). I will look into using the GTH-q10 PP if i cant get the accuracy i need with the q2 basis-set, so thanks for the suggestion. Thanks Richard On Tuesday, September 11, 2018 at 11:31:31 AM UTC+1, Richard Fogarty wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Dear all, I'm trying to use a custom basis-set for Mg in CP2K but am getting unphysical results; I suspect the reason is that i'm making a mistake with the basis set formatting. The simplest unphysical result is for a calculation on a single atom, whereby the ground state has p-orbitals (rather than s) fully occupied (see attached *.inp and *.cpout files). The basis set is generated in an external program using the following steps: 1) A calculation is carried out on an Mg atom with the s-shell occupied (neutral atom, no net spin). This calculation yields a list of grid points (distances from the nucleus, due to the spherical symmetry), and the value of each shell at these grid points (which I'll call \phi_{r}). I'm using the same pseudopotential ("Mg GTH-PBE-q2") in this calculation as in the subsequent CP2K calculations. 2) The value of \phi_{r} is multiplied by sqrt((2l+1))*(r**l) 3) Gaussians are fit to the data from step 2. Im loading the exponents and coefficients from step 3) into CP2K. One example is attached (file MG_TEST_BASIS). Note that the basis set attached leads to reasonable results for a single atom in the external program (where i know im entering it in the correct format). Any help would be greatly appreciated. Thanks in advance, Richard Misc info: This is using cp2k-6.1 in serial mode (cp2k.sopt executable) </div></blockquote></div>