Bonding, multiplicity and quantum chemistry for FeP2 I’m trying to do some quantum chemical calculations for the linear molecule $\ce{FeP2}$ in the gas phase as well as its crystal (orthorhombic symmetry like here). I am lead to believe that in both cases iron has an oxidation state of +6, and phosphorous has an oxidation state of −3. My questions are:


Are such oxidation states a reasonable assumption for this molecule?
Would the molecule normally be a singlet (multiplicity of one)?
What quantum chemistry methods would be appropriate for this system?
Admittedly it is vacuum phase, but are you certain about your oxidation state assignments?  "nearly temperature independent susceptibility of -(8.8±0.7)centerdot10-6SI (at room temperature)"

doi:10.1016/j.jpcs.2013.04.015 
https://sciborg.uwaterloo.ca/~lfnazar/publications/Electrochem_Solid-State_Lett_6_8_A162-A165_2003.pdf  
doi:10.1021/ja301173q  
http://www.staff.uni-bayreuth.de/~bt220235/refs/HPR_29_235.pdf  
doi:10.1088/0031-8949/4/3/010 (given)