Ab_init stress perturbation theory - Department of Physics and ...

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Symmetry with the strain perturbation • The reduced-zone k sample determined for (space group / strain) is (1) (1) used for K H 0 , Sternheimer, and 1′ H 0 – The full-zone sample specified in input data must have the full space group symmetry (enforced by test). • Loop on (ipert1, idir1) for 1 st -order wave functions restricted by input variables (rfstrs, rfdir) but not by symmetry – This could be improved, but would have limited impact on performance (1) • Inner loop on (ipert2, idir2) in 1′ H 0 calculations is carried over all strain and atomic displacement terms – piezoelectric contribution is computed if d/dk wf’s are avaialble (2) 0 H 0 • All strain and internal-strain tensor elements are computed, using the full zone k sample – It is more efficient here to keep loops on strains and displacements inside routines like nonlop.f – The reduced zone for pairs of perturbations would seldom be reduced much anyway
XC non-linear core correction • On the reduced real-space grid, electron charge depends only on −1 Ω • Model core charge has a detailed dependence on – Resulting analysis is rather complex Ξ ij • Core charges must be extremely smooth functions to avoid significant convergence errors – Reason: Strain and atomic position derivatives of the xc self-interaction of a single core don’t cancel point-by-point on the grid, but only in the integral – Inconsistencies in the treatment of the core charges and their derivatives in some Src_2psp/psp*cc.f routines makes matters worse
Page 1 and 2: Implementation of the Strain Pertur
Page 3 and 4: Strain tensor h ab as a perturbatio
Page 5 and 6: Abinit reduced coordinate (~) formu
Page 7 and 8: Stress and strain notation Cartesia
Page 9 and 10: DFPT for elastic and piezoelectric
Page 11 and 12: Design of development process • F
Page 13 and 14: Design of development process (cont
Page 15 and 16: Subroutines for strain perturbation
Page 17: Nonlocal pseudopotential strain der
Page 21 and 22: Strain perturbation for metals •
Page 23 and 24: 2DTE terms in output file • Mix o
Page 25 and 26: Input file for anaddb run dieflag 3
Page 27 and 28: Global comparison with numerical de
Page 29 and 30: Future development, continued • P
Page 31 and 32: Mathematica for nonlocal psp, , con

Ab_init stress perturbation theory - Department of Physics and ...

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