notebooks: fix missing attributions in BM2

Address usnistgov#1495

Fix some mistaken attributions for the free energy terms in
BM2. These are carry overs from the original benchmark paper.

benchmarks/benchmark2.ipynb

@@ -173,13 +173,14 @@
     "stress the numerical solver while not making the problem intractable.\n",
     "\n",
     "In this benchmark problem, the free energy of the system is based on\n",
-    "the formulation presented in Ref. [ZHU][] and is expressed as\n",
+    "a more general formulation of that presented in Ref. [ZHU][]. Specifically, the free energy here includes the concentration gradient energy as outlined in [WBM1][] and is expressed as\n",
     "\n",
     "$$\n",
     "F=\\int_{V}\\left(f_{chem}\\left(c,\\eta_{1},...\\eta_{p}\\right)+\\frac{\\kappa_{c}}{2}|\\nabla\n",
     "c|^{2}+\\sum_{i=1}^{p}\\frac{\\kappa_{\\eta}}{2}|\\nabla\\eta_{i}|^{2}\\right)dV\n",
     "$$\n",
     "\n",
+    "where the concentration gradient energy is \n",
     "where $\\kappa_{c}$ and $\\kappa_{\\eta}$ are the gradient energy\n",
     "coefficients for $c$ and $\\eta_{i}$, respectively. While the model in\n",
     "Ref. [ZHU][] follows the Kim-Kim-Suzuki ([KKS][]) formulation for\n",
@@ -268,6 +269,7 @@
     "[ZHU]: http://dx.doi.org/10.1016/j.actamat.2004.02.032\n",
     "[KKS]: https://doi.org/10.1103/PhysRevE.60.7186\n",
     "[WBM]: https://doi.org/10.1103/PhysRevA.45.7424\n",
+    "[WBM1]: https://doi.org/10.1103/PhysRevE.47.1893\n",
     "[CAHN]: http://dx.doi.org/10.1016/0001-6160(61)90182-1\n",
     "[ELLIOT]: http://dx.doi.org/10.1007/BF01396363\n",
     "[ALLEN]: http://dx.doi.org/10.1016/0001-6160(79)90196-2\n"
@@ -1437,7 +1439,7 @@
  "metadata": {
   "anaconda-cloud": {},
   "kernelspec": {
-   "display_name": "Python [default]",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
   },
@@ -1451,7 +1453,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.1"
+   "version": "3.6.4"
   }
  },
  "nbformat": 4,

benchmarks/benchmark2.ipynb.raw.html

@@ -209,12 +209,13 @@ <h2 id="Free-energy-and-dynamics">Free energy and dynamics<a class="anchor-link"
 setting $p=4$, a value commonly used in superalloy models; this will
 stress the numerical solver while not making the problem intractable.</p>
 <p>In this benchmark problem, the free energy of the system is based on
-the formulation presented in Ref. <a href="http://dx.doi.org/10.1016/j.actamat.2004.02.032">ZHU</a> and is expressed as</p>
+a more general formulation of that presented in Ref. <a href="http://dx.doi.org/10.1016/j.actamat.2004.02.032">ZHU</a>. Specifically, the free energy here includes the concentration gradient energy as outlined in <a href="https://doi.org/10.1103/PhysRevE.47.1893">WBM1</a> and is expressed as</p>
 <p>$$
 F=\int_{V}\left(f_{chem}\left(c,\eta_{1},...\eta_{p}\right)+\frac{\kappa_{c}}{2}|\nabla
 c|^{2}+\sum_{i=1}^{p}\frac{\kappa_{\eta}}{2}|\nabla\eta_{i}|^{2}\right)dV
 $$</p>
-<p>where $\kappa_{c}$ and $\kappa_{\eta}$ are the gradient energy
+<p>where the concentration gradient energy is 
+where $\kappa_{c}$ and $\kappa_{\eta}$ are the gradient energy
 coefficients for $c$ and $\eta_{i}$, respectively. While the model in
 Ref. <a href="http://dx.doi.org/10.1016/j.actamat.2004.02.032">ZHU</a> follows the Kim-Kim-Suzuki (<a href="https://doi.org/10.1103/PhysRevE.60.7186">KKS</a>) formulation for
 interfacial energy, we use the
@@ -3185,10 +3186,10 @@ <h4 id="Figure-2:-initial-$c$-for-(a),-(b)-and-(c)">Figure 2: initial $c$ for (a
 
 
 
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