Dear Pwscf users: I have some questions about IFC from pwscf. I have read some threads about interatomic force constants in PWSCF maillist. I get confused when trying to analysis the IFC of NiTi alloy, and also the example06 AsAl.
1. F(R) and R=(i-1)*a + (j-1)*b +(k-1)*c. It means F(1 2 1) should equal to F(1 1 2) and F(2 1 1) for cubic lattice. But in B2 NiTi alloy ( CsCl strucuture) F(1 1 2) = F(1 2 1) /= F(2 1 1). and in example06 F(2 1 1) = F(1 1 2) /= F(1 2 1). It seems some extra-things added to some direction. Why? 2. How to interpret the "1 1 1 1" section, F_{xx}^{1,1}(0). Does it means the force along x axis on Atom1 when Atom1 has a small displacement along the x direction? 3. The section after the "diagonalizing the dynamical matrix". I find the vectors in xx.dyn file xx.vec file (after matdyn.x) are different, rotated. Are these vectors eigen-displacements or just eigen-vector after diagonalizing? Best regards Dr. Zhou Bo Northwest University, Xi'an China NiTi.fc ... 6 6 6 1 1 1 1 1 1 1 4.30811843056E-02 2 1 1 1.49655475926E-02 3 1 1 7.47266388889E-04 4 1 1 -2.16783699074E-03 5 1 1 7.47266388889E-04 6 1 1 1.49655475926E-02 1 2 1 2.68996333333E-03 2 2 1 6.60210833333E-04 3 2 1 3.81960555556E-04 4 2 1 -2.61037222222E-04 5 2 1 3.81960555556E-04 6 2 1 6.60210833333E-04 1 3 1 -6.84333333333E-06 2 3 1 -6.65476851852E-05 3 3 1 -2.73466666667E-05 4 3 1 -1.06576851852E-04 5 3 1 -2.73466666667E-05 6 3 1 -6.65476851852E-05 1 4 1 4.48548611111E-05 2 4 1 -1.11791388889E-04 3 4 1 -1.06166666667E-05 4 4 1 -2.20306944444E-05 5 4 1 -1.06166666667E-05 6 4 1 -1.11791388889E-04 1 5 1 -6.84333333333E-06 2 5 1 -6.65476851852E-05 3 5 1 -2.73466666667E-05 4 5 1 -1.06576851852E-04 5 5 1 -2.73466666667E-05 6 5 1 -6.65476851852E-05 1 6 1 2.68996333333E-03 2 6 1 6.60210833333E-04 3 6 1 3.81960555556E-04 4 6 1 -2.61037222222E-04 5 6 1 3.81960555556E-04 6 6 1 6.60210833333E-04 1 1 2 2.68996333333E-03 2 1 2 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4 6 -6.13445370370E-05 3 4 6 7.55775925926E-05 4 4 6 -1.15009259259E-05 5 4 6 7.55775925926E-05 6 4 6 -6.13445370370E-05 1 5 6 1.78201250000E-04 2 5 6 1.02706111111E-04 3 5 6 -6.21652777778E-05 4 5 6 1.27609722222E-05 5 5 6 -6.21652777778E-05 6 5 6 1.02706111111E-04 1 6 6 1.07580273148E-03 2 6 6 -8.68419537037E-04 3 6 6 -1.26556851852E-04 4 6 6 4.42628240741E-05 5 6 6 -1.26556851852E-04 6 6 6 -8.68419537037E-04 1 1 1 2 1 1 1 -8.74218916667E-03 2 1 1 -8.74218976551E-03 3 1 1 -2.35019119479E-03 4 1 1 -7.60084259259E-05 5 1 1 -7.60088052061E-05 ... -------------- next part -------------- An HTML attachment was scrubbed... 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