duchl06 wrote: > hi,Gabriele Sclauzero > thanks for your advice and hoping your further guide. > i am reading a paper "Charge-Transfer-Based Mechanism for > Half-Metallicity and Ferromagnetism in one-Dimensional > OrganometallicSandwich Molecular Wires" > http://pubs.acs.org/doi/abs/10.1021/ja804053a > in this paper they consider a sandwich molecular wires (such as 1D > (VBz)? wire, (MnCp)? wire, Bz is benzene, Cp** is cyclopentadienyl), and > they said "Furthermore, we investigate the effect of doubling the unit > cell size along the SMW direction to evaluate the ground state of > ferromagnetic (FM), antiferromagnetic (AFM), and diamagnetic (DM) > con?gurations in our spin-polarized calculations with structural > optimization,
In this paper, I think they refer to a non-magnetic ground-state as "DM configuration". A priori you do not know if the DFT ground state (which does not necessarily always correspond to the true physical GS) will be FM, AFM or non-magnetic. You have to allow the system to "explore" an enlarged phase space with non-zero magnetization and see if the energy of a magnetic configuration (either FM or AFM) is lower than the non-magnetic solution. Actually, if the GS is non-magnetic, you should end to the non-magnetic GS even if you start from a magnetic configuration (unless you get trapped in some local minimum). I think that's why \Delta E in table 1 of the paper you pointed out is always negative (or not given): if the GS is magnetic, it will have a lower energy than the lowest energy non-magnetic solution, otherwise the GS is not magnetic and a spin-polarized calculation will give the same GS of a non-spin polarized one. HTH GS > and assess possibility of the Peierls transition." > > > (and i also found in some other papers when they do not know the groud > state is FM or DM, they would always say "To examine the stability of > the local magnetic state, we calculate the energy difference between the > diamagnetic and ferromagnetic states". > > ?2009-10-02?"Gabriele Sclauzero" <sclauzer at sissa.it> ??? >> >> >>duchl06 wrote: >>> thanks every one's reply! >>> hi, Hui Wang >>> the example you supplied is a calculation for a antiferromagnetic >>> material, i mean how to set the start magnetic moment for the >>> diamagnetic material, >> >>Diamagnetic material in absence of an external magnetic field should have no >>net magnetic >>moment per atom, if I'm not wrong. So it is not clear to me what do you want >>to study and >>if all these suggestions are pointing you to the correct solution. If you >>want to study a >>diamagnetic material in absence of magnetic field there should be no need for >>a >>spin-polarized calculation. >>So, just to agree on the starting point of your question: what you mean with >>diamagnetic >>material is really what people usually refer to? Can you give us more details >>on the >>system you want to address? What properties do you want to study? ... >> >>Regards, >> >> >>GS >> -- o ------------------------------------------------ o | Gabriele Sclauzero, PhD Student | | c/o: SISSA & CNR-INFM Democritos, | | via Beirut 2-4, 34014 Trieste (Italy) | | email: sclauzer at sissa.it | | phone: +39 040 3787 511 | | skype: gurlonotturno | o ------------------------------------------------ o
