Dear Sirs, I did some calculations with GaN (struct file in attachment) to compare the difference in energy and electric field gradient between the use of spin-polarization or not.
The calculations were done using the commands init_lapw -b -ecut -8 -numk 480 -rkmax 7 (-sp) run(sp)_lapw -p -ec 0.00001 -cc 0.0001 -fc 0.5 and the results were the following :ENE = -7995.60614872 (no spin-polarization) :ENE = -7995.60614871 (spin-polarization) :EFG001 = 0.57937 (no sp) :EFG001 = 0.57931 (sp) so they basically give the same. Then, I relaxed the structure using run(sp)_lapw -p -ec 0.00001 -cc 0.0001 -fc 0.5 -min and the results were :POS001 = 0.66667 0.33333 0.00002 (no sp) :POS001 = 0.66667 0.33333 0.00000 (sp) :POS002 = 0.66667 0.33333 0.37662 (no sp) :POS002 = 0.66667 0.33333 0.37701 (sp) :ENE = -7995.60615476 (no sp) :ENE = -7995.60615035 (sp) :EFG001 = 0.45038 (no sp) :EFG001 = 0.58801 (sp) so they gave different final positions and very different :EFG, as a consequence. However, if I use the final structure from the minimization without spin-polarization and do a calculation with spin-polarization (both from the beginning, using the previous commands), I get equal values :ENE = -7995.60615467 (no sp) :ENE = -7995.60615466 (sp) :EFG001 = 0.45036 (no sp) :EFG001 = 0.45034 (sp) and if I use the final structure from the minimization with spin-polarization and do a calculation without spin-polarization, I also get equal values :ENE = -7995.60614842 (no sp) :ENE = -7995.60614842 (sp) :EFG001 = 0.58272 (no sp) :EFG001 = 0.58271 (sp) This means that the only thing that I am getting different between them is the atomic positions during the minimization, since I always get the same :ENE and :EFG if both calculations are done with the same struct file. Is there any reason for this to happen? Which values for :ENE, :EFG and :POS should I consider the best, the spin-polarized ones or the ones without spin-polarization? Best regards, Marcelo
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