Fix(xc): align PW DeltaSpin sigma_y sign with LCAO path

PW basis had incorrect sign for the off-diagonal (sigma_y) coefficients
in the DeltaSpin Hamiltonian contribution:

  PW (before):   [1]=(+λ_y)  [2]=(-λ_y)  ← WRONG
  LCAO (fixed):  [1]=(-λ_y)  [2]=(+λ_y)  ← CORRECT

For σ_y = [[0,-i],[i,0]]:
  H_{up,dn}  = λ_x·σ_x + λ_y·σ_y = λ_x - i·λ_y  → coeff imag = -λ_y
  H_{dn,up}  = λ_x·σ_x + λ_y·σ_y = λ_x + i·λ_y  → coeff imag = +λ_y

Files fixed:
- op_pw_proj.cpp: onsite projection DeltaSpin coefficient
- force_op.cpp: DeltaSpin force kernel coefficient
- stress_op.cpp: DeltaSpin stress kernel coefficient

Author: dyzheng

source/source_pw/module_pwdft/kernels/force_op.cpp

@@ -406,9 +406,9 @@ struct cal_force_nl_op<FPTYPE, base_device::DEVICE_CPU>
                 int iat = iat0 + ia;
                 int sum = sum0 + ia * nproj;
                 const std::complex<FPTYPE> coefficients0(lambda[iat*3+2], 0.0);
-                const std::complex<FPTYPE> coefficients1(lambda[iat*3] , lambda[iat*3+1]);
-                const std::complex<FPTYPE> coefficients2(lambda[iat*3] , -1 * lambda[iat*3+1]);
-                const std::complex<FPTYPE> coefficients3(-1 * lambda[iat*3+2], 0.0);
+                const std::complex<FPTYPE> coefficients1(lambda[iat*3] , -lambda[iat*3+1]);
+                const std::complex<FPTYPE> coefficients2(lambda[iat*3] , lambda[iat*3+1]);
+                const std::complex<FPTYPE> coefficients3(-lambda[iat*3+2], 0.0);
                 for (int ib = 0; ib < nbands_occ; ib++)
                 {
                     FPTYPE local_force[3] = {0, 0, 0};

source/source_pw/module_pwdft/kernels/stress_op.cpp

@@ -359,9 +359,9 @@ struct cal_stress_nl_op<FPTYPE, base_device::DEVICE_CPU>
                 if (npol == 2)
                 {
                     const std::complex<FPTYPE> coefficients0(lambda[iat*3+2], 0.0);
-                    const std::complex<FPTYPE> coefficients1(lambda[iat*3] , lambda[iat*3+1]);
-                    const std::complex<FPTYPE> coefficients2(lambda[iat*3] , -1 * lambda[iat*3+1]);
-                    const std::complex<FPTYPE> coefficients3(-1 * lambda[iat*3+2], 0.0);
+                    const std::complex<FPTYPE> coefficients1(lambda[iat*3] , -lambda[iat*3+1]);
+                    const std::complex<FPTYPE> coefficients2(lambda[iat*3] , lambda[iat*3+1]);
+                    const std::complex<FPTYPE> coefficients3(-lambda[iat*3+2], 0.0);
                     for (int ib = 0; ib < nbands_occ; ib++)
                     {
                         const int ib2 = ib * 2;

source/source_pw/module_pwdft/op_pw_proj.cpp

@@ -163,9 +163,9 @@ void OnsiteProj<OperatorPW<T, Device>>::cal_ps_delta_spin(const int npol, const
         for(int iat=0;iat<this->ucell->nat;iat++)
         {
             tmp_lambda_coeff[iat * 4] = std::complex<double>(lambda[iat][2], 0.0);
-            tmp_lambda_coeff[iat * 4 + 1] = std::complex<double>(lambda[iat][0], lambda[iat][1]);
-            tmp_lambda_coeff[iat * 4 + 2] = std::complex<double>(lambda[iat][0], -1 * lambda[iat][1]);
-            tmp_lambda_coeff[iat * 4 + 3] = std::complex<double>(-1 * lambda[iat][2], 0.0);
+            tmp_lambda_coeff[iat * 4 + 1] = std::complex<double>(lambda[iat][0], -lambda[iat][1]);
+            tmp_lambda_coeff[iat * 4 + 2] = std::complex<double>(lambda[iat][0], lambda[iat][1]);
+            tmp_lambda_coeff[iat * 4 + 3] = std::complex<double>(-lambda[iat][2], 0.0);
         }
     }
     syncmem_complex_h2d_op()(this->lambda_coeff, tmp_lambda_coeff.data(), this->ucell->nat * 4);