WIP: Filter the symmetries when using ForwardDiff

src/external/spglib.jl

@@ -61,7 +61,7 @@ function spglib_cell(model::Model, magnetic_moments)
 end
 
 
-@timing function spglib_get_symmetry(lattice::AbstractMatrix{<:AbstractFloat}, atom_groups,
+@timing function spglib_get_symmetry(lattice, atom_groups,
                                      positions, magnetic_moments=[];
                                      tol_symmetry=SYMMETRY_TOLERANCE)
     lattice = Matrix{Float64}(lattice)  # spglib operates in double precision

src/workarounds/forwarddiff_rules.jl

@@ -113,17 +113,42 @@ function build_fft_plans!(tmp::AbstractArray{Complex{T}}) where {T<:ForwardDiff.
     ipFFT, opFFT, ipBFFT, opBFFT
 end
 
-# determine symmetry operations only from primal lattice values
+# versions of abs and is_approx_integer that operate on both the value and the partials
+abs_value_partials(x) = abs(x)
+abs_value_partials(x::ForwardDiff.Dual) = abs(x) + sum(abs, ForwardDiff.partials(x))
+function is_approx_integer_value_partials(x; kwargs...)
+    return is_approx_integer(x; kwargs) &&
+        all(y -> is_approx_integer(y; kwargs...), ForwardDiff.partials(x))
+end
+
 function spglib_get_symmetry(lattice::AbstractMatrix{<:ForwardDiff.Dual}, atom_groups, positions,
-                             magnetic_moments=[]; kwargs...)
-    spglib_get_symmetry(ForwardDiff.value.(lattice), atom_groups, positions,
-                        magnetic_moments; kwargs...)
+                             magnetic_moments=[]; tol_symmetry=SYMMETRY_TOLERANCE)
+    syms = spglib_get_symmetry(ForwardDiff.value.(lattice), atom_groups, positions,
+                        magnetic_moments; tol_symmetry)
+    # Only keep those symmetries that respect the deformation of the lattice
+    filter(syms) do ((W, w))
+        Wcart = lattice * W / lattice
+        maximum(abs_value_partials, Wcart'Wcart - I) > tol_symmetry
+    end
 end
-function spglib_atoms(atom_groups,
-                      positions::AbstractVector{<:AbstractVector{<:ForwardDiff.Dual}},
-                      magnetic_moments)
+function spglib_get_symmetry(lattice, atom_groups,
+                             positions::AbstractVector{<:AbstractVector{<:ForwardDiff.Dual}},
+                             magnetic_moments=[]; tol_symmetry=SYMMETRY_TOLERANCE)
     positions_value = [ForwardDiff.value.(pos) for pos in positions]
-    spglib_atoms(atom_groups, positions_value, magnetic_moments)
+    spglib_get_symmetry(lattice, atom_groups, positions_value,
+                        magnetic_moments; tol_symmetry)
+    # Only keep those symmetries that respect the displacements of the atoms
+    filter(syms) do ((W, w))
+        for group in atom_groups
+            group_positions = positions[group]
+            for coord in group_positions
+                if !any(c -> is_approx_integer_value_partials(W * coord + w - c; tol_symmetry), group_positions)
+                    return false
+                end
+            end
+        end
+        return true
+    end
 end
 
 function _is_well_conditioned(A::AbstractArray{<:ForwardDiff.Dual}; kwargs...)