Simplify momentum initialization in example input files (#2309)

* Simplify momentum initialization in example input files

* Update benchmarks

* Trigger Build

* Apply suggestions from code review

Co-authored-by: Edoardo Zoni <59625522+EZoni@users.noreply.github.com>

* Add more amrex prefix

* Remove using namespace amrex in PlasmaInjector.cpp

* Fix compilation with OpenPMD

Co-authored-by: Edoardo Zoni <59625522+EZoni@users.noreply.github.com>

13 files changed, 88 insertions, 97 deletions

diff --git a/Examples/Modules/boosted_diags/inputs_3d_slice b/Examples/Modules/boosted_diags/inputs_3d_slice
index 0737d7d55..15a2df477 100644
--- a/Examples/Modules/boosted_diags/inputs_3d_slice
+++ b/Examples/Modules/boosted_diags/inputs_3d_slice
@@ -45,7 +45,7 @@ electrons.charge = -q_e
 electrons.mass = m_e
 electrons.injection_style = NUniformPerCell
 electrons.num_particles_per_cell_each_dim = 1 1 1
-electrons.momentum_distribution_type = "gaussian"
+electrons.momentum_distribution_type = "at_rest"
 electrons.xmin = -120.e-6
 electrons.xmax =  120.e-6
 electrons.ymin = -120.e-6
@@ -61,7 +61,7 @@ ions.charge = q_e
 ions.mass = m_p
 ions.injection_style = NUniformPerCell
 ions.num_particles_per_cell_each_dim = 1 1 1
-ions.momentum_distribution_type = "gaussian"
+ions.momentum_distribution_type = "at_rest"
 ions.xmin = -120.e-6
 ions.xmax =  120.e-6
 ions.ymin = -120.e-6
diff --git a/Examples/Modules/dive_cleaning/inputs_3d b/Examples/Modules/dive_cleaning/inputs_3d
index 1c8da5464..35f46f1dd 100644
--- a/Examples/Modules/dive_cleaning/inputs_3d
+++ b/Examples/Modules/dive_cleaning/inputs_3d
@@ -28,10 +28,7 @@ beam.y_m = 0.
 beam.z_m = 0.e-6
 beam.npart = 20000
 beam.q_tot = -1.e-20
-beam.momentum_distribution_type = "gaussian"
-beam.ux_m = 0.0
-beam.uy_m = 0.0
-beam.uz_m = 0.0
+beam.momentum_distribution_type = "at_rest"
 
 diagnostics.diags_names = diag1
 diag1.intervals = 8
diff --git a/Examples/Modules/ionization/inputs_2d_bf_rt b/Examples/Modules/ionization/inputs_2d_bf_rt
index db4fe089c..ec60bff1b 100644
--- a/Examples/Modules/ionization/inputs_2d_bf_rt
+++ b/Examples/Modules/ionization/inputs_2d_bf_rt
@@ -32,7 +32,7 @@ ions.zmin =  0.
 ions.zmax =  50.e-6
 ions.profile = constant
 ions.density = 1.
-ions.momentum_distribution_type = constant
+ions.momentum_distribution_type = at_rest
 ions.do_field_ionization = 1
 ions.ionization_initial_level = 2
 ions.ionization_product_species = electrons
@@ -47,7 +47,7 @@ electrons.zmin = 0.
 electrons.zmax =  50.e-6
 electrons.profile = constant
 electrons.density = 2.
-electrons.momentum_distribution_type = constant
+electrons.momentum_distribution_type = at_rest
 electrons.do_continuous_injection=1
 
 lasers.names        = laser1
diff --git a/Examples/Modules/ionization/inputs_2d_rt b/Examples/Modules/ionization/inputs_2d_rt
index 0549d19be..873610c4b 100644
--- a/Examples/Modules/ionization/inputs_2d_rt
+++ b/Examples/Modules/ionization/inputs_2d_rt
@@ -27,7 +27,7 @@ ions.zmin =  5.e-6
 ions.zmax = 15.e-6
 ions.profile = constant
 ions.density = 1.
-ions.momentum_distribution_type = constant
+ions.momentum_distribution_type = at_rest
 ions.do_field_ionization = 1
 ions.ionization_initial_level = 2
 ions.ionization_product_species = electrons
@@ -41,7 +41,7 @@ electrons.zmin = 1.
 electrons.zmax = 15.e-6
 electrons.profile = constant
 electrons.density = 2.
-electrons.momentum_distribution_type = constant
+electrons.momentum_distribution_type = at_rest
 
 lasers.names        = laser1
 laser1.profile      = Gaussian
diff --git a/Examples/Modules/nci_corrector/inputs_2d b/Examples/Modules/nci_corrector/inputs_2d
index 6430d5d3e..24855c63e 100644
--- a/Examples/Modules/nci_corrector/inputs_2d
+++ b/Examples/Modules/nci_corrector/inputs_2d
@@ -59,11 +59,8 @@ ions.injection_style = "NUniformPerCell"
 ions.num_particles_per_cell_each_dim = 1 1 1
 ions.profile = constant
 ions.density = 1.e29  # number of electrons per m^3
-ions.momentum_distribution_type = "gaussian"
-ions.ux_th  = 0. # uth the std of the (unitless) momentum
-ions.uy_th  = 0. # uth the std of the (unitless) momentum
-ions.uz_th  = 0. # uth the std of the (unitless) momentum
-ions.uz_m  = 1000.  # Mean momentum along z (unitless)
+ions.momentum_distribution_type = "constant"
+ions.uz  = 1000.  # Momentum along z (unitless)
 ions.xmin = -10.e-6
 ions.xmax = +10.e-6
 ions.ymin = -10.e-6
diff --git a/Examples/Modules/qed/breit_wheeler/inputs_2d b/Examples/Modules/qed/breit_wheeler/inputs_2d
index b3ef8a57e..3137261ba 100644
--- a/Examples/Modules/qed/breit_wheeler/inputs_2d
+++ b/Examples/Modules/qed/breit_wheeler/inputs_2d
@@ -45,8 +45,8 @@ p1.profile = "constant"
 p1.num_particles_per_cell_each_dim = 32 32
 p1.density = 1e19
 p1.profile = "constant"
-p1.momentum_distribution_type = "gaussian"
-p1.ux_m = 2000.0
+p1.momentum_distribution_type = "constant"
+p1.ux = 2000.0
 ##########QED####################
 p1.do_qed_breit_wheeler = 1
 p1.qed_breit_wheeler_ele_product_species = ele1
@@ -59,8 +59,8 @@ p2.profile = "constant"
 p2.num_particles_per_cell_each_dim = 32 32
 p2.density = 1e19
 p2.profile = "constant"
-p2.momentum_distribution_type = "gaussian"
-p2.uy_m = 5000.0
+p2.momentum_distribution_type = "constant"
+p2.uy = 5000.0
 ##########QED####################
 p2.do_qed_breit_wheeler = 1
 p2.qed_breit_wheeler_ele_product_species = ele2
@@ -73,8 +73,8 @@ p3.profile = "constant"
 p3.num_particles_per_cell_each_dim = 32 32
 p3.density = 1e19
 p3.profile = "constant"
-p3.momentum_distribution_type = "gaussian"
-p3.uz_m = 10000.0
+p3.momentum_distribution_type = "constant"
+p3.uz = 10000.0
 ##########QED####################
 p3.do_qed_breit_wheeler = 1
 p3.qed_breit_wheeler_ele_product_species = ele3
@@ -87,10 +87,10 @@ p4.profile = "constant"
 p4.num_particles_per_cell_each_dim = 32 32
 p4.density = 1e19
 p4.profile = "constant"
-p4.momentum_distribution_type = "gaussian"
-p4.ux_m = 57735.02691896
-p4.uy_m = 57735.02691896
-p4.uz_m = 57735.02691896
+p4.momentum_distribution_type = "constant"
+p4.ux = 57735.02691896
+p4.uy = 57735.02691896
+p4.uz = 57735.02691896
 ##########QED####################
 p4.do_qed_breit_wheeler = 1
 p4.qed_breit_wheeler_ele_product_species = ele4
@@ -103,7 +103,7 @@ ele1.injection_style = nuniformpercell
 ele1.num_particles_per_cell_each_dim = 0 0
 ele1.profile = constant
 ele1.density = 0.0
-ele1.momentum_distribution_type = "gaussian"
+ele1.momentum_distribution_type = "at_rest"
 ele1.do_not_push = 1
 ele1.do_qed_quantum_sync = 1
 ele1.qed_quantum_sync_phot_product_species = dummy_phot
@@ -113,7 +113,7 @@ ele2.injection_style = nuniformpercell
 ele2.num_particles_per_cell_each_dim = 1 1
 ele2.profile = constant
 ele2.density = 0.0
-ele2.momentum_distribution_type = "gaussian"
+ele2.momentum_distribution_type = "at_rest"
 ele2.do_not_push = 1
 ele2.do_qed_quantum_sync = 1
 ele2.qed_quantum_sync_phot_product_species = dummy_phot
@@ -123,7 +123,7 @@ ele3.injection_style = nuniformpercell
 ele3.num_particles_per_cell_each_dim = 1 1
 ele3.profile = constant
 ele3.density = 0.0
-ele3.momentum_distribution_type = "gaussian"
+ele3.momentum_distribution_type = "at_rest"
 ele3.do_not_push = 1
 ele3.do_qed_quantum_sync = 1
 ele3.qed_quantum_sync_phot_product_species = dummy_phot
@@ -133,7 +133,7 @@ ele4.injection_style = nuniformpercell
 ele4.num_particles_per_cell_each_dim = 1 1
 ele4.profile = constant
 ele4.density = 0.0
-ele4.momentum_distribution_type = "gaussian"
+ele4.momentum_distribution_type = "at_rest"
 ele4.do_not_push = 1
 ele4.do_qed_quantum_sync = 1
 ele4.qed_quantum_sync_phot_product_species = dummy_phot
@@ -143,7 +143,7 @@ pos1.injection_style = nuniformpercell
 pos1.num_particles_per_cell_each_dim = 0 0
 pos1.profile = constant
 pos1.density = 0.0
-pos1.momentum_distribution_type = "gaussian"
+pos1.momentum_distribution_type = "at_rest"
 pos1.do_not_push = 1
 pos1.do_qed_quantum_sync = 1
 pos1.qed_quantum_sync_phot_product_species = dummy_phot
@@ -153,7 +153,7 @@ pos2.injection_style = nuniformpercell
 pos2.num_particles_per_cell_each_dim = 0 0
 pos2.profile = constant
 pos2.density = 0.0
-pos2.momentum_distribution_type = "gaussian"
+pos2.momentum_distribution_type = "at_rest"
 pos2.do_not_push = 1
 pos2.do_qed_quantum_sync = 1
 pos2.qed_quantum_sync_phot_product_species = dummy_phot
@@ -163,7 +163,7 @@ pos3.injection_style = nuniformpercell
 pos3.num_particles_per_cell_each_dim = 0 0
 pos3.profile = constant
 pos3.density = 0.0
-pos3.momentum_distribution_type = "gaussian"
+pos3.momentum_distribution_type = "at_rest"
 pos3.do_not_push = 1
 pos3.do_qed_quantum_sync = 1
 pos3.qed_quantum_sync_phot_product_species = dummy_phot
@@ -173,7 +173,7 @@ pos4.injection_style = nuniformpercell
 pos4.num_particles_per_cell_each_dim = 0 0
 pos4.profile = constant
 pos4.density = 0.0
-pos4.momentum_distribution_type = "gaussian"
+pos4.momentum_distribution_type = "at_rest"
 pos4.do_not_push = 1
 pos4.do_qed_quantum_sync = 1
 pos4.qed_quantum_sync_phot_product_species = dummy_phot
@@ -183,7 +183,7 @@ dummy_phot.injection_style = nuniformpercell
 dummy_phot.num_particles_per_cell_each_dim = 0 0
 dummy_phot.profile = constant
 dummy_phot.density = 0.0
-dummy_phot.momentum_distribution_type = "gaussian"
+dummy_phot.momentum_distribution_type = "at_rest"
 
 #################################
 
diff --git a/Examples/Modules/qed/breit_wheeler/inputs_3d b/Examples/Modules/qed/breit_wheeler/inputs_3d
index 73a8d4f77..b58fd773b 100644
--- a/Examples/Modules/qed/breit_wheeler/inputs_3d
+++ b/Examples/Modules/qed/breit_wheeler/inputs_3d
@@ -45,8 +45,8 @@ p1.profile = "constant"
 p1.num_particles_per_cell_each_dim = 8 8 4
 p1.density = 1e19
 p1.profile = "constant"
-p1.momentum_distribution_type = "gaussian"
-p1.ux_m = 2000.0
+p1.momentum_distribution_type = "constant"
+p1.ux = 2000.0
 ##########QED####################
 p1.do_qed_breit_wheeler = 1
 p1.qed_breit_wheeler_ele_product_species = ele1
@@ -59,8 +59,8 @@ p2.profile = "constant"
 p2.num_particles_per_cell_each_dim = 8 8 4
 p2.density = 1e19
 p2.profile = "constant"
-p2.momentum_distribution_type = "gaussian"
-p2.uy_m = 5000.0
+p2.momentum_distribution_type = "constant"
+p2.uy = 5000.0
 ##########QED####################
 p2.do_qed_breit_wheeler = 1
 p2.qed_breit_wheeler_ele_product_species = ele2
@@ -73,8 +73,8 @@ p3.profile = "constant"
 p3.num_particles_per_cell_each_dim = 8 8 4
 p3.density = 1e19
 p3.profile = "constant"
-p3.momentum_distribution_type = "gaussian"
-p3.uz_m = 10000.0
+p3.momentum_distribution_type = "constant"
+p3.uz = 10000.0
 ##########QED####################
 p3.do_qed_breit_wheeler = 1
 p3.qed_breit_wheeler_ele_product_species = ele3
@@ -87,10 +87,10 @@ p4.profile = "constant"
 p4.num_particles_per_cell_each_dim = 8 8 4
 p4.density = 1e19
 p4.profile = "constant"
-p4.momentum_distribution_type = "gaussian"
-p4.ux_m = 57735.02691896
-p4.uy_m = 57735.02691896
-p4.uz_m = 57735.02691896
+p4.momentum_distribution_type = "constant"
+p4.ux = 57735.02691896
+p4.uy = 57735.02691896
+p4.uz = 57735.02691896
 ##########QED####################
 p4.do_qed_breit_wheeler = 1
 p4.qed_breit_wheeler_ele_product_species = ele4
@@ -103,7 +103,7 @@ ele1.injection_style = nuniformpercell
 ele1.num_particles_per_cell_each_dim = 0 0 0
 ele1.profile = constant
 ele1.density = 0.0
-ele1.momentum_distribution_type = "gaussian"
+ele1.momentum_distribution_type = "at_rest"
 ele1.do_not_push = 1
 ele1.do_qed_quantum_sync = 1
 ele1.qed_quantum_sync_phot_product_species = dummy_phot
@@ -113,7 +113,7 @@ ele2.injection_style = nuniformpercell
 ele2.num_particles_per_cell_each_dim = 0 0 0
 ele2.profile = constant
 ele2.density = 0.0
-ele2.momentum_distribution_type = "gaussian"
+ele2.momentum_distribution_type = "at_rest"
 ele2.do_not_push = 1
 ele2.do_qed_quantum_sync = 1
 ele2.qed_quantum_sync_phot_product_species = dummy_phot
@@ -123,7 +123,7 @@ ele3.injection_style = nuniformpercell
 ele3.num_particles_per_cell_each_dim = 0 0 0
 ele3.profile = constant
 ele3.density = 0.0
-ele3.momentum_distribution_type = "gaussian"
+ele3.momentum_distribution_type = "at_rest"
 ele3.do_not_push = 1
 ele3.do_qed_quantum_sync = 1
 ele3.qed_quantum_sync_phot_product_species = dummy_phot
@@ -133,7 +133,7 @@ ele4.injection_style = nuniformpercell
 ele4.num_particles_per_cell_each_dim = 0 0 0
 ele4.profile = constant
 ele4.density = 0.0
-ele4.momentum_distribution_type = "gaussian"
+ele4.momentum_distribution_type = "at_rest"
 ele4.do_not_push = 1
 ele4.do_qed_quantum_sync = 1
 ele4.qed_quantum_sync_phot_product_species = dummy_phot
@@ -143,7 +143,7 @@ pos1.injection_style = nuniformpercell
 pos1.num_particles_per_cell_each_dim = 0 0 0
 pos1.profile = constant
 pos1.density = 0.0
-pos1.momentum_distribution_type = "gaussian"
+pos1.momentum_distribution_type = "at_rest"
 pos1.do_not_push = 1
 pos1.do_qed_quantum_sync = 1
 pos1.qed_quantum_sync_phot_product_species = dummy_phot
@@ -153,7 +153,7 @@ pos2.injection_style = nuniformpercell
 pos2.num_particles_per_cell_each_dim = 0 0 0
 pos2.profile = constant
 pos2.density = 0.0
-pos2.momentum_distribution_type = "gaussian"
+pos2.momentum_distribution_type = "at_rest"
 pos2.do_not_push = 1
 pos2.do_qed_quantum_sync = 1
 pos2.qed_quantum_sync_phot_product_species = dummy_phot
@@ -163,7 +163,7 @@ pos3.injection_style = nuniformpercell
 pos3.num_particles_per_cell_each_dim = 0 0 0
 pos3.profile = constant
 pos3.density = 0.0
-pos3.momentum_distribution_type = "gaussian"
+pos3.momentum_distribution_type = "at_rest"
 pos3.do_not_push = 1
 pos3.do_qed_quantum_sync = 1
 pos3.qed_quantum_sync_phot_product_species = dummy_phot
@@ -173,7 +173,7 @@ pos4.injection_style = nuniformpercell
 pos4.num_particles_per_cell_each_dim = 0 0 0
 pos4.profile = constant
 pos4.density = 0.0
-pos4.momentum_distribution_type = "gaussian"
+pos4.momentum_distribution_type = "at_rest"
 pos4.do_not_push = 1
 pos4.do_qed_quantum_sync = 1
 pos4.qed_quantum_sync_phot_product_species = dummy_phot
@@ -183,7 +183,7 @@ dummy_phot.injection_style = nuniformpercell
 dummy_phot.num_particles_per_cell_each_dim = 0 0 0
 dummy_phot.profile = constant
 dummy_phot.density = 0.0
-dummy_phot.momentum_distribution_type = "gaussian"
+dummy_phot.momentum_distribution_type = "at_rest"
 
 #################################
 
diff --git a/Examples/Modules/qed/quantum_synchrotron/inputs_2d b/Examples/Modules/qed/quantum_synchrotron/inputs_2d
index 5cf34129a..a7c05d278 100644
--- a/Examples/Modules/qed/quantum_synchrotron/inputs_2d
+++ b/Examples/Modules/qed/quantum_synchrotron/inputs_2d
@@ -45,8 +45,8 @@ p1.profile = "constant"
 p1.num_particles_per_cell_each_dim = 32 32
 p1.density = 1e1
 p1.profile = "constant"
-p1.momentum_distribution_type = "gaussian"
-p1.ux_m = 10.0
+p1.momentum_distribution_type = "constant"
+p1.ux = 10.0
 ##########QED####################
 p1.do_qed_quantum_sync = 1
 p1.qed_quantum_sync_phot_product_species = qsp_1
@@ -58,8 +58,8 @@ p2.profile = "constant"
 p2.num_particles_per_cell_each_dim = 32 32
 p2.density = 1e1
 p2.profile = "constant"
-p2.momentum_distribution_type = "gaussian"
-p2.uy_m = 100.0
+p2.momentum_distribution_type = "constant"
+p2.uy = 100.0
 ##########QED####################
 p2.do_qed_quantum_sync = 1
 p2.qed_quantum_sync_phot_product_species = qsp_2
@@ -71,8 +71,8 @@ p3.profile = "constant"
 p3.num_particles_per_cell_each_dim = 32 32
 p3.density = 1e1
 p3.profile = "constant"
-p3.momentum_distribution_type = "gaussian"
-p3.uz_m = 1000.0
+p3.momentum_distribution_type = "constant"
+p3.uz = 1000.0
 ##########QED####################
 p3.do_qed_quantum_sync = 1
 p3.qed_quantum_sync_phot_product_species = qsp_3
@@ -84,10 +84,10 @@ p4.profile = "constant"
 p4.num_particles_per_cell_each_dim = 32 32
 p4.density = 1e1
 p4.profile = "constant"
-p4.momentum_distribution_type = "gaussian"
-p4.ux_m = 5773.502691896
-p4.uy_m = 5773.502691896
-p4.uz_m = 5773.502691896
+p4.momentum_distribution_type = "constant"
+p4.ux = 5773.502691896
+p4.uy = 5773.502691896
+p4.uz = 5773.502691896
 ##########QED####################
 p4.do_qed_quantum_sync = 1
 p4.qed_quantum_sync_phot_product_species = qsp_4
@@ -99,7 +99,7 @@ qsp_1.injection_style = nuniformpercell
 qsp_1.num_particles_per_cell_each_dim = 0 0
 qsp_1.profile = constant
 qsp_1.density = 0.0
-qsp_1.momentum_distribution_type = "gaussian"
+qsp_1.momentum_distribution_type = "at_rest"
 qsp_1.do_qed_breit_wheeler = 1
 qsp_1.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_1.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -109,7 +109,7 @@ qsp_2.injection_style = nuniformpercell
 qsp_2.num_particles_per_cell_each_dim = 0 0
 qsp_2.profile = constant
 qsp_2.density = 0.0
-qsp_2.momentum_distribution_type = "gaussian"
+qsp_2.momentum_distribution_type = "at_rest"
 qsp_2.do_qed_breit_wheeler = 1
 qsp_2.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_2.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -119,7 +119,7 @@ qsp_3.injection_style = nuniformpercell
 qsp_3.num_particles_per_cell_each_dim = 0 0
 qsp_3.profile = constant
 qsp_3.density = 0.0
-qsp_3.momentum_distribution_type = "gaussian"
+qsp_3.momentum_distribution_type = "at_rest"
 qsp_3.do_qed_breit_wheeler = 1
 qsp_3.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_3.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -129,7 +129,7 @@ qsp_4.injection_style = nuniformpercell
 qsp_4.num_particles_per_cell_each_dim = 0 0
 qsp_4.profile = constant
 qsp_4.density = 0.0
-qsp_4.momentum_distribution_type = "gaussian"
+qsp_4.momentum_distribution_type = "at_rest"
 qsp_4.do_qed_breit_wheeler = 1
 qsp_4.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_4.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -141,14 +141,14 @@ dummy_ele.injection_style = nuniformpercell
 dummy_ele.num_particles_per_cell_each_dim = 0 0
 dummy_ele.profile = constant
 dummy_ele.density = 0.0
-dummy_ele.momentum_distribution_type = "gaussian"
+dummy_ele.momentum_distribution_type = "at_rest"
 
 dummy_pos.species_type = "positron"
 dummy_pos.injection_style = nuniformpercell
 dummy_pos.num_particles_per_cell_each_dim = 0 0
 dummy_pos.profile = constant
 dummy_pos.density = 0.0
-dummy_pos.momentum_distribution_type = "gaussian"
+dummy_pos.momentum_distribution_type = "at_rest"
 
 #################################
 
diff --git a/Examples/Modules/qed/quantum_synchrotron/inputs_3d b/Examples/Modules/qed/quantum_synchrotron/inputs_3d
index 8b1ff7e89..e77366b1e 100644
--- a/Examples/Modules/qed/quantum_synchrotron/inputs_3d
+++ b/Examples/Modules/qed/quantum_synchrotron/inputs_3d
@@ -45,8 +45,8 @@ p1.profile = "constant"
 p1.num_particles_per_cell_each_dim = 8 8 4
 p1.density = 1e1
 p1.profile = "constant"
-p1.momentum_distribution_type = "gaussian"
-p1.ux_m = 10.0
+p1.momentum_distribution_type = "constant"
+p1.ux = 10.0
 ##########QED####################
 p1.do_qed_quantum_sync = 1
 p1.qed_quantum_sync_phot_product_species = qsp_1
@@ -58,8 +58,8 @@ p2.profile = "constant"
 p2.num_particles_per_cell_each_dim = 8 8 4
 p2.density = 1e1
 p2.profile = "constant"
-p2.momentum_distribution_type = "gaussian"
-p2.uy_m = 100.0
+p2.momentum_distribution_type = "constant"
+p2.uy = 100.0
 ##########QED####################
 p2.do_qed_quantum_sync = 1
 p2.qed_quantum_sync_phot_product_species = qsp_2
@@ -71,8 +71,8 @@ p3.profile = "constant"
 p3.num_particles_per_cell_each_dim = 8 8 4
 p3.density = 1e1
 p3.profile = "constant"
-p3.momentum_distribution_type = "gaussian"
-p3.uz_m = 1000.0
+p3.momentum_distribution_type = "constant"
+p3.uz = 1000.0
 ##########QED####################
 p3.do_qed_quantum_sync = 1
 p3.qed_quantum_sync_phot_product_species = qsp_3
@@ -84,10 +84,10 @@ p4.profile = "constant"
 p4.num_particles_per_cell_each_dim = 8 8 4
 p4.density = 1e1
 p4.profile = "constant"
-p4.momentum_distribution_type = "gaussian"
-p4.ux_m = 5773.502691896
-p4.uy_m = 5773.502691896
-p4.uz_m = 5773.502691896
+p4.momentum_distribution_type = "constant"
+p4.ux = 5773.502691896
+p4.uy = 5773.502691896
+p4.uz = 5773.502691896
 ##########QED####################
 p4.do_qed_quantum_sync = 1
 p4.qed_quantum_sync_phot_product_species = qsp_4
@@ -99,7 +99,7 @@ qsp_1.injection_style = nuniformpercell
 qsp_1.num_particles_per_cell_each_dim = 0 0 0
 qsp_1.profile = constant
 qsp_1.density = 0.0
-qsp_1.momentum_distribution_type = "gaussian"
+qsp_1.momentum_distribution_type = "at_rest"
 qsp_1.do_qed_breit_wheeler = 1
 qsp_1.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_1.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -109,7 +109,7 @@ qsp_2.injection_style = nuniformpercell
 qsp_2.num_particles_per_cell_each_dim = 0 0 0
 qsp_2.profile = constant
 qsp_2.density = 0.0
-qsp_2.momentum_distribution_type = "gaussian"
+qsp_2.momentum_distribution_type = "at_rest"
 qsp_2.do_qed_breit_wheeler = 1
 qsp_2.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_2.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -119,7 +119,7 @@ qsp_3.injection_style = nuniformpercell
 qsp_3.num_particles_per_cell_each_dim = 0 0 0
 qsp_3.profile = constant
 qsp_3.density = 0.0
-qsp_3.momentum_distribution_type = "gaussian"
+qsp_3.momentum_distribution_type = "at_rest"
 qsp_3.do_qed_breit_wheeler = 1
 qsp_3.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_3.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -129,7 +129,7 @@ qsp_4.injection_style = nuniformpercell
 qsp_4.num_particles_per_cell_each_dim = 0 0 0
 qsp_4.profile = constant
 qsp_4.density = 0.0
-qsp_4.momentum_distribution_type = "gaussian"
+qsp_4.momentum_distribution_type = "at_rest"
 qsp_4.do_qed_breit_wheeler = 1
 qsp_4.qed_breit_wheeler_ele_product_species = dummy_ele
 qsp_4.qed_breit_wheeler_pos_product_species = dummy_pos
@@ -141,14 +141,14 @@ dummy_ele.injection_style = nuniformpercell
 dummy_ele.num_particles_per_cell_each_dim = 0 0 0
 dummy_ele.profile = constant
 dummy_ele.density = 0.0
-dummy_ele.momentum_distribution_type = "gaussian"
+dummy_ele.momentum_distribution_type = "at_rest"
 
 dummy_pos.species_type = "positron"
 dummy_pos.injection_style = nuniformpercell
 dummy_pos.num_particles_per_cell_each_dim = 0 0 0
 dummy_pos.profile = constant
 dummy_pos.density = 0.0
-dummy_pos.momentum_distribution_type = "gaussian"
+dummy_pos.momentum_distribution_type = "at_rest"
 
 #################################
 
diff --git a/Examples/Modules/qed/schwinger/inputs_3d_schwinger b/Examples/Modules/qed/schwinger/inputs_3d_schwinger
index c8f70992f..b9b81b284 100644
--- a/Examples/Modules/qed/schwinger/inputs_3d_schwinger
+++ b/Examples/Modules/qed/schwinger/inputs_3d_schwinger
@@ -55,8 +55,8 @@ ele_schwinger.profile = "constant"
 pos_schwinger.profile = "constant"
 ele_schwinger.density = 0
 pos_schwinger.density = 0
-ele_schwinger.momentum_distribution_type = "gaussian"
-pos_schwinger.momentum_distribution_type = "gaussian"
+ele_schwinger.momentum_distribution_type = "at_rest"
+pos_schwinger.momentum_distribution_type = "at_rest"
 
 #################################
 ############## QED ##############
diff --git a/Examples/Modules/relativistic_space_charge_initialization/inputs_3d b/Examples/Modules/relativistic_space_charge_initialization/inputs_3d
index 2e41c4edd..c864f9fa1 100644
--- a/Examples/Modules/relativistic_space_charge_initialization/inputs_3d
+++ b/Examples/Modules/relativistic_space_charge_initialization/inputs_3d
@@ -28,10 +28,10 @@ beam.y_m = 0.
 beam.z_m = 0.e-6
 beam.npart = 20000
 beam.q_tot = -1.e-20
-beam.momentum_distribution_type = "gaussian"
-beam.ux_m = 0.0
-beam.uy_m = 0.0
-beam.uz_m = 100.0
+beam.momentum_distribution_type = "constant"
+beam.ux = 0.0
+beam.uy = 0.0
+beam.uz = 100.0
 
 # Diagnostics
 diagnostics.diags_names = diag1
diff --git a/Examples/Modules/resampling/inputs_leveling_thinning b/Examples/Modules/resampling/inputs_leveling_thinning
index b53237352..2d91e8e60 100644
--- a/Examples/Modules/resampling/inputs_leveling_thinning
+++ b/Examples/Modules/resampling/inputs_leveling_thinning
@@ -22,7 +22,7 @@ resampled_part1.injection_style = NRandomPerCell
 resampled_part1.num_particles_per_cell = 400
 resampled_part1.profile = constant
 resampled_part1.density = 1.
-resampled_part1.momentum_distribution_type = constant
+resampled_part1.momentum_distribution_type = at_rest
 resampled_part1.do_not_deposit = 1
 resampled_part1.do_not_gather = 1
 resampled_part1.do_not_push = 1
@@ -48,7 +48,7 @@ resampled_part2.profile = parse_density_function
 # within the cell as the two random variables. Here, we have a distribution with standard deviation
 # sigma = 1/sqrt(2) and mean 4*sigma.
 resampled_part2.density_function(x,y,z) = 2.*sqrt(2.)+sqrt(-log(x))*cos(2*pi*z)
-resampled_part2.momentum_distribution_type = constant
+resampled_part2.momentum_distribution_type = at_rest
 resampled_part2.do_not_deposit = 1
 resampled_part2.do_not_gather = 1
 resampled_part2.do_not_push = 1
diff --git a/Examples/Modules/space_charge_initialization/inputs_3d b/Examples/Modules/space_charge_initialization/inputs_3d
index 322cb3aad..d6370c97e 100644
--- a/Examples/Modules/space_charge_initialization/inputs_3d
+++ b/Examples/Modules/space_charge_initialization/inputs_3d
@@ -27,10 +27,7 @@ beam.y_m = 0.
 beam.z_m = 0.e-6
 beam.npart = 20000
 beam.q_tot = -1.e-20
-beam.momentum_distribution_type = "gaussian"
-beam.ux_m = 0.0
-beam.uy_m = 0.0
-beam.uz_m = 0.0
+beam.momentum_distribution_type = "at_rest"
 
 # Diagnostics
 diagnostics.diags_names = diag1