For S1, which has the energy formula of 2.0*mixed - 1.0*triplet, your choice is &LOW_SPIN_ROKS ENERGY_SCALING 2.0 -2.0 SPIN_CONFIGURATION 1 2 SPIN_CONFIGURATION 1 1 &END LOW_SPIN_ROKS Note that whatever you specify in low_spin_roks will be added to the high-spin Hamiltonian. <div class="gmail_quote">On Fri, Apr 13, 2012 at 6:07 AM, StKolev <<a href="mailto:sko...@mnet.bg">sko...@mnet.bg</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Does this mean that the two singly occupied orbitals should be alpha and their energy should be added to that of the system without scaling? Is this enough for singlet state with 2 unpaired electrons, I read articles on ROKS and read the help of CP2K but could not determine this. &LOW_SPIN_ROKS ENERGY_SCALING 1.0 SPIN_CONFIGURATION 1 1 &END Another question, why does it give error when you label the system singlet? And the system should be labeled triplet to run the simulation? <div class="HOEnZb"><div class="h5"> -- You received this message because you are subscribed to the Google Groups "cp2k" group. To post to this group, send email to <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a>. To unsubscribe from this group, send email to <a href="mailto:cp2k%2Bun...@googlegroups.com">cp2k+uns...@googlegroups.com</a>. For more options, visit this group at <a href="http://groups.google.com/group/cp2k?hl=en" target="_blank">http://groups.google.com/group/cp2k?hl=en</a>. </div></div></blockquote></div>