PSATD: Implement First-Order Equations (#3466)

* Implement First-Order PSATD Equations

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Fix Unused Parameter Warning

* Fix RZ Build

* Fix Normalization of G to Match PML

* Add CI Test: 3D Uniform Plasma

* Cleaning

* Update 2D CI Checksums

* Update 3D CI Checksums

* Add F,G to CI Checksums of `uniform_plasma_multiJ`

* Allow User to Choose First-Order v. Second-Order

* Add WARPX_ALWAYS_ASSERT_WITH_MESSAGE

* Rename New Class `PsatdAlgorithmFirstOrder`

* Remove Inline Comment

* Update RZ CI Checksums

* Fix inline comment

* Use auxiliary variables to avoid divisions

* Use auxiliary variables to avoid divisions

* Make `nci_psatd_stability` dir and merge inputs

* Move all Galilean tests to `nci_psatd_stability`

* Fix CI

* Fix index for backward FFT of J

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

2 files changed, 18 insertions, 3 deletions

diff --git a/Source/Utils/WarpXAlgorithmSelection.H b/Source/Utils/WarpXAlgorithmSelection.H
index c3160cfad..936fd3d2b 100644
--- a/Source/Utils/WarpXAlgorithmSelection.H
+++ b/Source/Utils/WarpXAlgorithmSelection.H
@@ -84,6 +84,13 @@ struct GatheringAlgo {
     };
 };
 
+struct PSATDSolutionType {
+    enum {
+        FirstOrder = 0,
+        SecondOrder = 1
+    };
+};
+
 struct JInTime {
     enum {
         Constant = 0,
@@ -93,8 +100,8 @@ struct JInTime {
 
 struct RhoInTime {
     enum {
-        Linear = 1,
-        Quadratic = 2
+        Constant = 0,
+        Linear = 1
     };
 };
 
diff --git a/Source/Utils/WarpXAlgorithmSelection.cpp b/Source/Utils/WarpXAlgorithmSelection.cpp
index b99459b46..c5ef16743 100644
--- a/Source/Utils/WarpXAlgorithmSelection.cpp
+++ b/Source/Utils/WarpXAlgorithmSelection.cpp
@@ -63,6 +63,12 @@ const std::map<std::string, int> gathering_algo_to_int = {
     {"default",             GatheringAlgo::EnergyConserving }
 };
 
+const std::map<std::string, int> psatd_solution_type_to_int = {
+    {"first-order", PSATDSolutionType::FirstOrder},
+    {"second-order", PSATDSolutionType::SecondOrder},
+    {"default", PSATDSolutionType::SecondOrder}
+};
+
 const std::map<std::string, int> J_in_time_to_int = {
     {"constant", JInTime::Constant},
     {"linear", JInTime::Linear},
@@ -70,8 +76,8 @@ const std::map<std::string, int> J_in_time_to_int = {
 };
 
 const std::map<std::string, int> rho_in_time_to_int = {
+    {"constant", RhoInTime::Constant},
     {"linear", RhoInTime::Linear},
-    {"quadratic", RhoInTime::Quadratic},
     {"default", RhoInTime::Linear}
 };
 
@@ -145,6 +151,8 @@ GetAlgorithmInteger( amrex::ParmParse& pp, const char* pp_search_key ){
         algo_to_int = charge_deposition_algo_to_int;
     } else if (0 == std::strcmp(pp_search_key, "field_gathering")) {
         algo_to_int = gathering_algo_to_int;
+    } else if (0 == std::strcmp(pp_search_key, "solution_type")) {
+        algo_to_int = psatd_solution_type_to_int;
     } else if (0 == std::strcmp(pp_search_key, "J_in_time")) {
         algo_to_int = J_in_time_to_int;
     } else if (0 == std::strcmp(pp_search_key, "rho_in_time")) {