1 files changed, 25 insertions, 0 deletions
diff --git a/Source/Particles/PhotonParticleContainer.cpp b/Source/Particles/PhotonParticleContainer.cpp
index 399892959..e6712657a 100644
--- a/Source/Particles/PhotonParticleContainer.cpp
+++ b/Source/Particles/PhotonParticleContainer.cpp
@@ -43,6 +43,11 @@ void PhotonParticleContainer::InitData()
 {
     AddParticles(0); // Note - add on level 0
 
+#ifdef WARPX_QED
+    if(do_qed_breit_wheeler)
+        InitTauBreitWheeler();
+#endif
+
     if (maxLevel() > 0) {
         Redistribute();  // We then redistribute
     }
@@ -118,3 +123,23 @@ PhotonParticleContainer::Evolve (int lev,
                                        t, dt);
 
 }
+
+#ifdef WARPX_QED
+// A function to initialize the Tau component according to the BW engine
+void PhotonParticleContainer::InitTauBreitWheeler()
+{
+    BL_PROFILE("PhotonParticleContainer::InitOpticalDepth");
+//Looping over all the particles
+int num_levels = finestLevel() + 1;
+for (int lev=0; lev < num_levels; ++lev)
+    for (WarpXParIter pti(*this, lev); pti.isValid(); ++pti){
+        auto taus = pti.GetAttribs(particle_comps["tau"]).dataPtr();
+        amrex::ParallelFor(
+            pti.numParticles(),
+            [=] AMREX_GPU_DEVICE (long i) {
+                taus[i] = warpx_breit_wheeler_get_optical_depth();
+            }
+        );
+    }
+}
+#endif