Fix: DeltaSpin energy fix (#7748)

* Fix(deltaspin): enable DeltaSpin constraint energy calculation for PW basis

- cal_escon(): replace is_Mi_converged gate with lambda_/Mi_ empty check
  to prevent segfault when uninitialized
- elecstate_pw: add get_spin_constrain_energy() override so PW basis
  computes DeltaSpin constraint energy (previously returned 0.0)
- elecstate_pw.h: declare get_spin_constrain_energy() override

Note: this fix enables escon computation for PW DeltaSpin but
lambda values from BFGS optimizer may differ from accel branch
due to energy functional convention differences. Full convergence
with accel requires lambda_loop.cpp migration.

* Fix(deltaspin): enable PW DeltaSpin constraint energy and update test refs

Source changes:
- cal_escon(): replace is_Mi_converged guard with lambda_/Mi_ empty check
  to prevent segfault when uninitialized (matching accel convention)
- elecstate_pw: add get_spin_constrain_energy() override so PW basis
  includes DeltaSpin constraint energy in total energy (was always 0)

Test refs regenerated for 7 cases with significant energy changes:
- 14_PW_DS_S4_XYZ, 15_PW_DS_S4_Z, 16_PW_DS_S4_XY
- 18_PW_DFTU_DS_S2_Z, 19_PW_DFTU_DS_S4_XY, 21_PW_DFTU_DS_S4_Z
- 41_PW_DS_S4_Thr10_XY

nspin=2 tests and ReadLam/Thr1e10 tests unchanged.

* Fix(deltaspin): fix pauli_to_moment My sign convention and enable PW escon

Source fixes:
- spin_constrain.h: fix My = -Im(occ1-occ2) → Im(occ1-occ2)
  The magnetic moment y-component had the wrong sign in the Pauli matrix
  transformation, causing incorrect Mi computation for nspin=4 DeltaSpin.
- cal_escon(): replace is_Mi_converged guard with lambda_/Mi_ empty check
- elecstate_pw: add get_spin_constrain_energy() for PW basis DeltaSpin

Refs regenerated for nspin=4 DeltaSpin cases: 14, 15, 16, 19, 21, 41
Test 18 unchanged, nspin=2 tests unchanged.

* Fix(build): link deltaspin sources into MODULE_ESTATE_elecstate_pw test

elecstate_pw.cpp now calls spinconstrain::SpinConstrain<
std::complex<double>>::getScInstance()/cal_escon() via the new
get_spin_constrain_energy() override. The MODULE_ESTATE_elecstate_pw
unit test compiles elecstate_pw.cpp directly but did not link the
deltaspin module, causing undefined-reference link errors in
BUILD_TESTING builds (test.yml and cuda.yml CI jobs).

Add spin_constrain.cpp to the test SOURCES, mirroring the existing
MODULE_LCAO_deltaspin_spin_constrain_test pattern.

* fix: add get_spin_constrain_energy stub to hsolver supplementary mock

ElecStatePW::get_spin_constrain_energy() is a new virtual override
that needs a definition in the vtable. Test targets (MODULE_HSOLVER_base,
MODULE_HSOLVER_pw, MODULE_HSOLVER_sdft) compile a mock implementation
of ElecStatePW methods instead of linking elecstate_pw.cpp, and were
missing a stub for this new method, causing:
  undefined reference to ElecStatePW::get_spin_constrain_energy()

---------

Co-authored-by: dyzheng <zhengdy@bjaisi.com>

Author: dyzheng

source/source_estate/elecstate_pw.cpp

@@ -8,6 +8,7 @@
 #include "source_base/timer.h"
 #include "source_hamilt/module_xc/xc_functional.h"
 #include "source_io/module_parameter/parameter.h"
+#include "source_lcao/module_deltaspin/spin_constrain.h"
 #include "source_pw/module_pwdft/vnl_pw.h"
 
 namespace elecstate {
@@ -56,6 +57,14 @@ ElecStatePW<T, Device>::~ElecStatePW()
     delmem_complex_op()(this->wfcr_another_spin);
 }
 
+template<typename T, typename Device>
+double ElecStatePW<T, Device>::get_spin_constrain_energy()
+{
+    spinconstrain::SpinConstrain<std::complex<double>>& sc
+        = spinconstrain::SpinConstrain<std::complex<double>>::getScInstance();
+    return sc.cal_escon();
+}
+
 template<typename T, typename Device>
 void ElecStatePW<T, Device>::init_rho_data() 
 {

source/source_estate/elecstate_pw.h

@@ -36,6 +36,8 @@ class ElecStatePW : public ElecState
 
     virtual void cal_tau(const psi::Psi<T, Device>& psi);
 
+    double get_spin_constrain_energy() override;
+
     //! calculate becsum for uspp
     void cal_becsum(const psi::Psi<T, Device>& psi);
 

source/source_estate/test/CMakeLists.txt

@@ -51,6 +51,7 @@ AddTest(
     ../elecstate.cpp
     ../occupy.cpp
     ../module_charge/charge_mpi.cpp
+    ../../source_lcao/module_deltaspin/spin_constrain.cpp
     ../../source_psi/psi.cpp
     ../../source_base/module_device/memory_op.cpp
 )

source/source_hsolver/test/hsolver_supplementary_mock.h

@@ -59,6 +59,12 @@ void ElecStatePW<T, Device>::cal_becsum(const psi::Psi<T, Device>& psi)
 {
 }
 
+template <typename T, typename Device>
+double ElecStatePW<T, Device>::get_spin_constrain_energy()
+{
+    return 0.0;
+}
+
 template class ElecStatePW<std::complex<float>, base_device::DEVICE_CPU>;
 template class ElecStatePW<std::complex<double>, base_device::DEVICE_CPU>;
 #if ((defined __CUDA) || (defined __ROCM))

source/source_lcao/module_deltaspin/spin_constrain.cpp

@@ -45,7 +45,7 @@ template <typename TK>
 double SpinConstrain<TK>::cal_escon()
 {
     this->escon_ = 0.0;
-    if (!this->is_Mi_converged)
+    if (this->lambda_.empty() || this->Mi_.empty())
     {
         return this->escon_;
     }

source/source_lcao/module_deltaspin/spin_constrain.h

@@ -79,7 +79,7 @@ inline ModuleBase::Vector3<double> pauli_to_moment(const std::complex<double> oc
 {
     return ModuleBase::Vector3<double>(
         weight * (occ[1] + occ[2]).real(),
-        -weight * (occ[1] - occ[2]).imag(),
+        weight * (occ[1] - occ[2]).imag(),
         weight * (occ[0] - occ[3]).real()
     );
 }

tests/17_DS_DFTU/14_PW_DS_S4_XYZ/result.ref

@@ -1,3 +1,3 @@
-etotref -6366.562922988214
-etotperatomref -3183.2814614941
-totaltimeref 4.23
+etotref -6369.19895097706
+etotperatomref -3184.59947548853
+totaltimeref 1.0

tests/17_DS_DFTU/15_PW_DS_S4_Z/result.ref

@@ -1,3 +1,3 @@
-etotref -6366.562433916121
-etotperatomref -3183.2812169581
-totaltimeref 4.26
+etotref -6369.198273166801
+etotperatomref -3184.5991365834007
+totaltimeref 1.0

tests/17_DS_DFTU/16_PW_DS_S4_XY/result.ref

@@ -1,3 +1,3 @@
-etotref -6366.562695059035
-etotperatomref -3183.2813475295
-totaltimeref 4.19
+etotref -6369.198274098935
+etotperatomref -3184.5991370494676
+totaltimeref 1.0

tests/17_DS_DFTU/19_PW_DFTU_DS_S4_XY/result.ref

@@ -1,3 +1,3 @@
-etotref -6355.9841673819892094
-etotperatomref -3177.9920836910
-totaltimeref 5.88
+etotref -6360.5554588729937677
+etotperatomref -3180.277729436497
+totaltimeref 1.0