doi:10.1103/PhysRevB.98.195108engNatoli, C.R.Kruger, P.Yoshimoto, Y.Bartolome, J.Bartolome, F.Simple model of the ground state and spin-orbital excitations of free and adsorbed Fe(II) phthalocyanine moleculesART-2018-108926We investigate the ground state and low-energy spin-orbital excitations of a single iron(II) phthalocyanine molecule in isolation and on an oxidized Cu(110) surface. Considering the subspace spanned by the three lowest spin-triplet states of (3)A(2g) and E-3(g) symmetry, we diagonalize the Hamiltonian made of the anisotropic spin-orbit interaction and the ligand field splitting Delta, defined as the energy difference between E-3(g) and (3)A(2g). We find that the ground state switches from a E-3(g)-like state with large orbital moment and out-of-plane easy axis for Delta < -60 meV to a (3)A(2g)-like singlet state with in-plane easy axis for Delta > -60 meV. The analysis of the first excited states in the two regimes explains the zero-field splitting data reported for beta-FePc as well as for FePc molecules adsorbed on an oxidized Cu(110) surface [N. Tsukahara et al., Phys. Rev. Lett. 102, 167203 (2009)]. Importantly, the calculated magnetic susceptibility obtained with the ab initio value Delta = 93 meV compares remarkably well with the experimental data of beta-FePc in the whole available temperature range of 1-300 K.2018http://zaguan.unizar.es/record/7601310.1103/PhysRevB.98.195108http://zaguan.unizar.es/record/76013oai:zaguan.unizar.es:76013info:eu-repo/grantAgreement/EUR/COST/MP1306-EUSPECinfo:eu-repo/grantAgreement/ES/DGA/FEDERinfo:eu-repo/grantAgreement/ES/DGA-FSE/E12-17R-RASMIAinfo:eu-repo/grantAgreement/ES/MINECO/MAT2017-83468-RPhysical Review B 98, 19 (2018), 195108 [10 pp]by-nchttp://creativecommons.org/licenses/by-nc/3.0/es/info:eu-repo/semantics/openAccess