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magnetic metallic states and magnetic moments increase with the substitution of As by Sb in LaOFeAs, BaFe$_{2}$As$_{2}$ and LiFeAs. 

However, the magnetic moments we obtained are 1.6 (2.3) µ$_{B}$ in LiFeAs (LiFeSb), 2.0 (2.5) µ$_{B}$ in BaFe$_{2}$As$_{2}$ (BaFe$_{2}$Sb$_{2}$) and 1.8 (2.2) µ$_{B}$ in LaOFeAs (LaOFeSb) $^{76}$, which are notably smaller than those obtained from the pseudopotential method $^{65,87}$. Further comparing the optimized lattice structures, we find that, while our results are in good agreement with 

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previous GGA calculations, such as LiFeAs calculated with VASP 85 and WIEN2k $^{86}$, there are large differences between our results and those of Refs. 65,87 as shown in Table I. Furthermore, in Table II, we show the com- parison between experimental and optimized structural data for BaFe$_{2}$As$_{2}$, where we find that our optimized structure agrees with the experimental one better than that from Ref. 65. Since the electronic band structure close to the Fermi level is sensitive to the lattice structure $^{20,88}$, the conclusion of Ref. 65 based on their optimized structures that there is no connection between Fermi surface nesting and magnetism is questionable. Therefore, we reinvestigate the nesting property of the Fermi surface. 

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Fig. 1 presents the comparison of normalized q - dependent Pauli susceptibilities at fixed q$_{z}$ = π between arsenides and antimonides in 111, 1111 and 122 com- pounds. The normalization factors are the susceptibili- ties of the corresponding arsenide for each type of com- pounds at q$_{0}$ = (0 , 0 , π ). We fix q$_{z}$ = π because of the fact that spins on iron are arranged antiferromagnetically along the z direction as observed in experiments $^{77–81}$. However, we checked that the conclusion drawn below will not be changed if q$_{z}$ = 0 is fixed. 

We find that in all Fe-based families, the situation is similar. Two peaks around q$_{0}$ = (0 , 0 , π ) and q$_{π}$ = ( π, π, π ) are detected in both arsenides and antimonides, and the peaks around ( π, π, π ) are always stronger than those around (0 , 0 , π ), indicating that the instability to- wards stripe-type antiferromagnetic ordering dominates, which is consistent with our spin-polarized GGA calcu- lations. Most importantly, we find that, in contrast to Ref. 65, the Pauli susceptibilities are also enhanced to- gether with the magnetizations when As is substituted by Sb in LaOFeAs, LiFeAs and BaFe$_{2}$As$_{2}$, which demon- 

