From 27f30c6a2d5cc6581da4461ecf87c168ee515b3f Mon Sep 17 00:00:00 2001
From: Ray Speth <speth@mit.edu>
Date: Fri, 9 Aug 2019 11:31:55 -0400
Subject: [PATCH] Use more precise atomic masses for deuterium and tritium

---
 data/inputs/elements.xml                      |  7 +++++--
 interfaces/cython/cantera/test/test_thermo.py |  4 ++--
 src/thermo/Elements.cpp                       | 13 ++++---------
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/data/inputs/elements.xml b/data/inputs/elements.xml
index e056f0e8b..e142383d5 100644
--- a/data/inputs/elements.xml
+++ b/data/inputs/elements.xml
@@ -8,6 +8,9 @@
  atomic weight" from the IUPAC Periodic Table is used. Available
  online at https://iupac.org/wp-content/uploads/2018/12/IUPAC_Periodic_Table-01Dec18.pdf
 
+ Values for deuterium and tritium are from: M. Wang et al. The AME2016 atomic
+ mass evaluation. Chinese Physics C. doi:10.1088/1674-1137/41/3/030003.
+
  The electron mass is the 2018 CODATA value.
 
  If no value is given in either source, it is because no stable isotopes of
@@ -22,7 +25,7 @@
              </source>
            </entropy298>
         </element>
-  <element name="D" atomicWt = "2.014102" atomicNumber = "1" >
+  <element name="D" atomicWt = "2.0141017781" atomicNumber = "1" >
            <entropy298 value = "72.480E3">
              <source>
         The standard entropy (1/2 D2 gas) was taken from the NIST-JANAF
@@ -31,7 +34,7 @@
              </source>
            </entropy298>
         </element>
-  <element name="Tr" atomicWt = "3.0160495" atomicNumber = "1" >
+  <element name="Tr" atomicWt = "3.0160492820" atomicNumber = "1" >
            <entropy298>
              <source>
         There is no reference state thermodynamic data tabulated
diff --git a/interfaces/cython/cantera/test/test_thermo.py b/interfaces/cython/cantera/test/test_thermo.py
index 8619c514f..6647adcb7 100644
--- a/interfaces/cython/cantera/test/test_thermo.py
+++ b/interfaces/cython/cantera/test/test_thermo.py
@@ -1311,13 +1311,13 @@ class TestElement(utilities.CanteraTest):
     def test_get_isotope(self):
         d_sym = ct.Element('D')
         self.assertEqual(d_sym.atomic_number, 1)
-        self.assertNear(d_sym.weight, 2.014102)
+        self.assertNear(d_sym.weight, 2.0141017781)
         self.assertEqual(d_sym.name, 'deuterium')
         self.assertEqual(d_sym.symbol, 'D')
 
         d_name = ct.Element('deuterium')
         self.assertEqual(d_name.atomic_number, 1)
-        self.assertNear(d_name.weight, 2.014102)
+        self.assertNear(d_name.weight, 2.0141017781)
         self.assertEqual(d_name.name, 'deuterium')
         self.assertEqual(d_name.symbol, 'D')
 
diff --git a/src/thermo/Elements.cpp b/src/thermo/Elements.cpp
index dfb3d1d26..55694e861 100644
--- a/src/thermo/Elements.cpp
+++ b/src/thermo/Elements.cpp
@@ -197,15 +197,10 @@ static struct atomicWeightData atomicWeightTable[] = {
  * The size of the table is given by the initial instantiation.
  */
 static struct isotopeWeightData isotopeWeightTable[] = {
-    // National Center for Biotechnology Information. PubChem Database.
-    // Deuterium, CID=24523, https://pubchem.ncbi.nlm.nih.gov/compound/Deuterium
-    // (accessed on Aug. 7, 2019)
-    {"D",  "deuterium", 2.014102, 1},
-
-    // National Center for Biotechnology Information. PubChem Database.
-    // Tritium, CID=24824, https://pubchem.ncbi.nlm.nih.gov/compound/Tritium
-    // (accessed on Aug. 7, 2019)
-    {"Tr", "tritium", 3.0160495, 1},
+    // M. Wang et al. The AME2016 atomic mass evaluation. Chinese Physics C.
+    // doi:10.1088/1674-1137/41/3/030003.
+    {"D",  "deuterium", 2.0141017781, 1},
+    {"Tr", "tritium", 3.0160492820, 1},
     {"E", "electron", ElectronMass * Avogadro, 0},
 };