diff --git a/src/data/isotopes.cpp b/src/data/isotopes.cpp
index cb3b5a52f7..6ac27b13a3 100644
--- a/src/data/isotopes.cpp
+++ b/src/data/isotopes.cpp
@@ -42,6 +42,22 @@ static std::vector<IsotopeData> sears91Data_ = {
     {Isotope::H_1, Elements::H, 1, "1/2(+)", 1.00783, -3.7406, 25.274, 1.7583, 80.27, 82.03, 0.3326},
     {Isotope::H_2, Elements::H, 2, "1(+)", 2.014, 6.671, 4.04, 5.592, 2.05, 7.64, 0.000519},
     {Isotope::H_3, Elements::H, 3, "1/2(+)", 3.01605, 4.792, -1.04, 2.89, 0.14, 3.03, 0},
+    {Isotope::H100D0, Elements::H, 10, "", 1.00797, -3.739, 0, 1.7568, 80.26, 82.02, 0.3326},
+    {Isotope::H90D10, Elements::H, 11, "", 1.108573, -2.698, 0.404, 2.14032, 72.43900000000001, 74.582, 0.2993919},
+    {Isotope::H80D20, Elements::H, 12, "", 1.209176, -1.657, 0.808, 2.52384, 64.61800000000001, 67.144, 0.2661838},
+    {Isotope::H70D30, Elements::H, 13, "", 1.309779, -0.6159999999999992, 1.2120000000000002, 2.90736, 56.797000000000004,
+     59.705999999999996, 0.2329757},
+    {Isotope::H60D40, Elements::H, 14, "", 1.410382, 0.42500000000000027, 1.616, 3.29088, 48.976, 52.267999999999994,
+     0.1997676},
+    {Isotope::H50D50, Elements::H, 15, "", 1.5109849999999998, 1.4660000000000002, 2.02, 3.6744, 41.155, 44.83, 0.1665595},
+    {Isotope::H40D60, Elements::H, 16, "", 1.611588, 2.5070000000000014, 2.4240000000000004, 4.05792, 33.33399999999999,
+     37.391999999999996, 0.13335139999999995},
+    {Isotope::H30D70, Elements::H, 17, "", 1.7121909999999998, 3.548000000000001, 2.8280000000000003, 4.44144,
+     25.512999999999995, 29.953999999999994, 0.10014329999999998},
+    {Isotope::H20D80, Elements::H, 18, "", 1.812794, 4.589, 3.232, 4.82496, 17.691999999999997, 22.516, 0.06693519999999999},
+    {Isotope::H10D90, Elements::H, 19, "", 1.9133969999999998, 5.630000000000001, 3.636, 5.20848, 9.870999999999999,
+     15.077999999999998, 0.03372709999999999},
+    {Isotope::H0D100, Elements::H, 20, "", 2.014, 6.671, 4.04, 5.592, 2.05, 7.64, 0.000519},
     {Isotope::He_Natural, Elements::He, 0, "", 4.0026, 3.26, 0, 1.34, 0, 1.34, 0.00747},
     {Isotope::He_3, Elements::He, 3, "1/2(+)", 3.01603, 5.74, -2.5, 4.42, 1.6, 6, 5333},
     {Isotope::He_4, Elements::He, 4, "0(+)", 4.0026, 3.26, 0, 1.34, 0, 1.34, 0},
@@ -473,6 +489,17 @@ Isotope isotope(Elements::Element Z, int A)
     return it->isotope();
 }
 
+// Return isotope data corresponding element and A (if it exists)
+const IsotopeData &isotopeData(Elements::Element Z, int A)
+{
+    auto it = std::find_if(sears91Data_.begin(), sears91Data_.end(),
+                           [Z, A](const auto &topeData) { return topeData.Z() == Z && topeData.A() == A; });
+    if (it == sears91Data_.end())
+        Messenger::exception("No isotope with A = {} available for element {}.\n", A, Elements::symbol(Z));
+
+    return *it;
+}
+
 // Return natural isotope for element (if it exists)
 Isotope naturalIsotope(Elements::Element Z)
 {
diff --git a/src/data/isotopes.h b/src/data/isotopes.h
index c741142a98..56ba48d214 100644
--- a/src/data/isotopes.h
+++ b/src/data/isotopes.h
@@ -17,6 +17,17 @@ enum Isotope
     H_1,
     H_2,
     H_3,
+    H100D0,
+    H90D10,
+    H80D20,
+    H70D30,
+    H60D40,
+    H50D50,
+    H40D60,
+    H30D70,
+    H20D80,
+    H10D90,
+    H0D100,
     He_Natural,
     He_3,
     He_4,
@@ -444,6 +455,8 @@ bool hasIsotope(Elements::Element Z, int A);
 std::vector<Isotope> isotopes(Elements::Element Z);
 // Return isotope enum corresponding element and A (if it exists)
 Isotope isotope(Elements::Element Z, int A);
+// Return isotope data corresponding element and A (if it exists)
+const IsotopeData &isotopeData(Elements::Element Z, int A);
 // Return natural isotope for element (if it exists)
 Isotope naturalIsotope(Elements::Element Z);
 // Return element (Z) of Isotope
diff --git a/src/main/cli.cpp b/src/main/cli.cpp
index cf35e590d9..c8782cc822 100644
--- a/src/main/cli.cpp
+++ b/src/main/cli.cpp
@@ -3,6 +3,7 @@
 
 #include "main/cli.h"
 #include "base/messenger.h"
+#include "data/isotopes.h"
 #include "main/version.h"
 #include <CLI/App.hpp>
 #include <CLI/Config.hpp>
@@ -19,6 +20,23 @@ int CLIOptions::parse(const int args, char **argv, bool isGUI, bool isParallel)
     // Add positionals
     auto inputFileOption = app.add_option("inputFile", inputFile_, "Input file to load")->check(CLI::ExistingFile);
 
+    // TEST Create some H isotope mixes
+    auto H = Sears91::isotopeData(Elements::H, 0);
+    auto D = Sears91::isotopeData(Elements::H, 2);
+    for (auto i = 0; i <= 10; ++i)
+    {
+        auto fracD = i * 0.1;
+        auto fracH = 1.0 - fracD;
+
+        // {Isotope::H_1, Elements::H, 1, "1/2(+)", 1.00783, -3.7406, 25.274, 1.7583, 80.27, 82.03, 0.3326},
+        Messenger::print("{{Isotope::H{}D{}, Elements::H, {}, \"\", {}, {}, {}, {}, {}, {}, {}}},\n", 100 - i * 10, i * 10,
+                         10 + i, H.mass() * fracH + D.mass() * fracD, H.boundCoherent() * fracH + D.boundCoherent() * fracD,
+                         H.boundIncoherent() * fracH + D.boundIncoherent() * fracD,
+                         H.boundCoherentXS() * fracH + D.boundCoherentXS() * fracD,
+                         H.boundIncoherentXS() * fracH + D.boundIncoherentXS() * fracD,
+                         H.totalXS() * fracH + D.totalXS() * fracD, H.absorptionXS() * fracH + D.absorptionXS() * fracD);
+    }
+
     // Basic Control
     app.add_option("-n,--iterations", nIterations_, "Number of iterations to run (default = 0)")->group("Basic Control");
     app.add_flag_callback(