diff --git a/docs/tour.ipynb b/docs/tour.ipynb
index 570dec0..0ee3d09 100644
--- a/docs/tour.ipynb
+++ b/docs/tour.ipynb
@@ -122,7 +122,7 @@
     },
     {
       "cell_type": "code",
-      "execution_count": 3,
+      "execution_count": 2,
       "metadata": {
         "colab": {
           "base_uri": "https://localhost:8080/",
@@ -134,10 +134,11 @@
       "outputs": [
         {
           "data": {
-            "application/3dmoljs_load.v0": "<div id=\"3dmolviewer_17142235959271243\"  style=\"position: relative; width: 640px; height: 480px;\">\n        <p id=\"3dmolwarning_17142235959271243\" style=\"background-color:#ffcccc;color:black\">3Dmol.js failed to load for some reason.  Please check your browser console for error messages.<br></p>\n        </div>\n<script>\n\nvar loadScriptAsync = function(uri){\n  return new Promise((resolve, reject) => {\n    //this is to ignore the existence of requirejs amd\n    var savedexports, savedmodule;\n    if (typeof exports !== 'undefined') savedexports = exports;\n    else exports = {}\n    if (typeof module !== 'undefined') savedmodule = module;\n    else module = {}\n\n    var tag = document.createElement('script');\n    tag.src = uri;\n    tag.async = true;\n    tag.onload = () => {\n        exports = savedexports;\n        module = savedmodule;\n        resolve();\n    };\n  var firstScriptTag = document.getElementsByTagName('script')[0];\n  firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);\n});\n};\n\nif(typeof $3Dmolpromise === 'undefined') {\n$3Dmolpromise = null;\n  $3Dmolpromise = loadScriptAsync('https://cdnjs.cloudflare.com/ajax/libs/3Dmol/2.1.0/3Dmol-min.js');\n}\n\nvar viewer_17142235959271243 = null;\nvar warn = document.getElementById(\"3dmolwarning_17142235959271243\");\nif(warn) {\n    warn.parentNode.removeChild(warn);\n}\n$3Dmolpromise.then(function() {\nviewer_17142235959271243 = $3Dmol.createViewer(document.getElementById(\"3dmolviewer_17142235959271243\"),{backgroundColor:\"white\"});\nviewer_17142235959271243.zoomTo();\n\tviewer_17142235959271243.addModel(\"3\\n\\nO\\t0.    \\t0.    \\t0.1165\\nH\\t 0.    \\t 0.7694\\t-0.4661\\nH\\t 0.    \\t-0.7694\\t-0.4661\\n\");\n\tviewer_17142235959271243.setStyle({\"stick\": {\"radius\": 0.1}});\nviewer_17142235959271243.render();\n});\n</script>",
+            "application/3dmoljs_load.v0": "<div id=\"3dmolviewer_17143862759373279\"  style=\"position: relative; width: 640px; height: 480px;\">\n        <p id=\"3dmolwarning_17143862759373279\" style=\"background-color:#ffcccc;color:black\">You appear to be running in JupyterLab (or JavaScript failed to load for some other reason).  You need to install the 3dmol extension: <br>\n        <tt>jupyter labextension install jupyterlab_3dmol</tt></p>\n        </div>\n<script>\n\nvar loadScriptAsync = function(uri){\n  return new Promise((resolve, reject) => {\n    //this is to ignore the existence of requirejs amd\n    var savedexports, savedmodule;\n    if (typeof exports !== 'undefined') savedexports = exports;\n    else exports = {}\n    if (typeof module !== 'undefined') savedmodule = module;\n    else module = {}\n\n    var tag = document.createElement('script');\n    tag.src = uri;\n    tag.async = true;\n    tag.onload = () => {\n        exports = savedexports;\n        module = savedmodule;\n        resolve();\n    };\n  var firstScriptTag = document.getElementsByTagName('script')[0];\n  firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);\n});\n};\n\nif(typeof $3Dmolpromise === 'undefined') {\n$3Dmolpromise = null;\n  $3Dmolpromise = loadScriptAsync('https://cdnjs.cloudflare.com/ajax/libs/3Dmol/2.0.4/3Dmol-min.js');\n}\n\nvar viewer_17143862759373279 = null;\nvar warn = document.getElementById(\"3dmolwarning_17143862759373279\");\nif(warn) {\n    warn.parentNode.removeChild(warn);\n}\n$3Dmolpromise.then(function() {\nviewer_17143862759373279 = $3Dmol.createViewer(document.getElementById(\"3dmolviewer_17143862759373279\"),{backgroundColor:\"white\"});\nviewer_17143862759373279.zoomTo();\n\tviewer_17143862759373279.addModel(\"3\\n\\nO\\t0.    \\t0.    \\t0.1165\\nH\\t 0.    \\t 0.7694\\t-0.4661\\nH\\t 0.    \\t-0.7694\\t-0.4661\\n\");\n\tviewer_17143862759373279.setStyle({\"stick\": {\"radius\": 0.1}});\nviewer_17143862759373279.render();\n});\n</script>",
             "text/html": [
-              "<div id=\"3dmolviewer_17142235959271243\"  style=\"position: relative; width: 640px; height: 480px;\">\n",
-              "        <p id=\"3dmolwarning_17142235959271243\" style=\"background-color:#ffcccc;color:black\">3Dmol.js failed to load for some reason.  Please check your browser console for error messages.<br></p>\n",
+              "<div id=\"3dmolviewer_17143862759373279\"  style=\"position: relative; width: 640px; height: 480px;\">\n",
+              "        <p id=\"3dmolwarning_17143862759373279\" style=\"background-color:#ffcccc;color:black\">You appear to be running in JupyterLab (or JavaScript failed to load for some other reason).  You need to install the 3dmol extension: <br>\n",
+              "        <tt>jupyter labextension install jupyterlab_3dmol</tt></p>\n",
               "        </div>\n",
               "<script>\n",
               "\n",
@@ -165,20 +166,20 @@
               "\n",
               "if(typeof $3Dmolpromise === 'undefined') {\n",
               "$3Dmolpromise = null;\n",
-              "  $3Dmolpromise = loadScriptAsync('https://cdnjs.cloudflare.com/ajax/libs/3Dmol/2.1.0/3Dmol-min.js');\n",
+              "  $3Dmolpromise = loadScriptAsync('https://cdnjs.cloudflare.com/ajax/libs/3Dmol/2.0.4/3Dmol-min.js');\n",
               "}\n",
               "\n",
-              "var viewer_17142235959271243 = null;\n",
-              "var warn = document.getElementById(\"3dmolwarning_17142235959271243\");\n",
+              "var viewer_17143862759373279 = null;\n",
+              "var warn = document.getElementById(\"3dmolwarning_17143862759373279\");\n",
               "if(warn) {\n",
               "    warn.parentNode.removeChild(warn);\n",
               "}\n",
               "$3Dmolpromise.then(function() {\n",
-              "viewer_17142235959271243 = $3Dmol.createViewer(document.getElementById(\"3dmolviewer_17142235959271243\"),{backgroundColor:\"white\"});\n",
-              "viewer_17142235959271243.zoomTo();\n",
-              "\tviewer_17142235959271243.addModel(\"3\\n\\nO\\t0.    \\t0.    \\t0.1165\\nH\\t 0.    \\t 0.7694\\t-0.4661\\nH\\t 0.    \\t-0.7694\\t-0.4661\\n\");\n",
-              "\tviewer_17142235959271243.setStyle({\"stick\": {\"radius\": 0.1}});\n",
-              "viewer_17142235959271243.render();\n",
+              "viewer_17143862759373279 = $3Dmol.createViewer(document.getElementById(\"3dmolviewer_17143862759373279\"),{backgroundColor:\"white\"});\n",
+              "viewer_17143862759373279.zoomTo();\n",
+              "\tviewer_17143862759373279.addModel(\"3\\n\\nO\\t0.    \\t0.    \\t0.1165\\nH\\t 0.    \\t 0.7694\\t-0.4661\\nH\\t 0.    \\t-0.7694\\t-0.4661\\n\");\n",
+              "\tviewer_17143862759373279.setStyle({\"stick\": {\"radius\": 0.1}});\n",
+              "viewer_17143862759373279.render();\n",
               "});\n",
               "</script>"
             ]
@@ -192,7 +193,7 @@
               "Structure(atomic_number=i64[3](numpy), position=f64[3,3](numpy))"
             ]
           },
-          "execution_count": 3,
+          "execution_count": 2,
           "metadata": {},
           "output_type": "execute_result"
         }
@@ -217,7 +218,7 @@
     },
     {
       "cell_type": "code",
-      "execution_count": 4,
+      "execution_count": 3,
       "metadata": {
         "colab": {
           "base_uri": "https://localhost:8080/"
@@ -228,6 +229,317 @@
       "outputs": [
         {
           "data": {
+            "text/html": [
+              "<div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>orbital</th>\n",
+              "      <th>coefficient</th>\n",
+              "      <th>norm</th>\n",
+              "      <th>center</th>\n",
+              "      <th>lmn</th>\n",
+              "      <th>alpha</th>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>primitive</th>\n",
+              "      <th></th>\n",
+              "      <th></th>\n",
+              "      <th></th>\n",
+              "      <th></th>\n",
+              "      <th></th>\n",
+              "      <th></th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>0</th>\n",
+              "      <td>0</td>\n",
+              "      <td>0.001831</td>\n",
+              "      <td>454.227134</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>5484.671875</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>1</th>\n",
+              "      <td>0</td>\n",
+              "      <td>0.013950</td>\n",
+              "      <td>109.734524</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>825.234924</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>2</th>\n",
+              "      <td>0</td>\n",
+              "      <td>0.068445</td>\n",
+              "      <td>36.191769</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>188.046951</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>3</th>\n",
+              "      <td>0</td>\n",
+              "      <td>0.232714</td>\n",
+              "      <td>13.992611</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>52.964500</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>4</th>\n",
+              "      <td>0</td>\n",
+              "      <td>0.470193</td>\n",
+              "      <td>5.939888</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>16.897570</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>5</th>\n",
+              "      <td>0</td>\n",
+              "      <td>0.358521</td>\n",
+              "      <td>2.663549</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>5.799635</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>6</th>\n",
+              "      <td>1</td>\n",
+              "      <td>-0.110778</td>\n",
+              "      <td>5.578151</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>15.539617</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>7</th>\n",
+              "      <td>1</td>\n",
+              "      <td>-0.148026</td>\n",
+              "      <td>1.862649</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>3.599934</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>8</th>\n",
+              "      <td>1</td>\n",
+              "      <td>1.130767</td>\n",
+              "      <td>0.720049</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>1.013762</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>9</th>\n",
+              "      <td>2</td>\n",
+              "      <td>1.000000</td>\n",
+              "      <td>0.266956</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>0.270006</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>10</th>\n",
+              "      <td>3</td>\n",
+              "      <td>0.070874</td>\n",
+              "      <td>43.978502</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[1, 0, 0]</td>\n",
+              "      <td>15.539617</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>11</th>\n",
+              "      <td>3</td>\n",
+              "      <td>0.339753</td>\n",
+              "      <td>7.068189</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[1, 0, 0]</td>\n",
+              "      <td>3.599934</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>12</th>\n",
+              "      <td>3</td>\n",
+              "      <td>0.727159</td>\n",
+              "      <td>1.449973</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[1, 0, 0]</td>\n",
+              "      <td>1.013762</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>13</th>\n",
+              "      <td>4</td>\n",
+              "      <td>0.070874</td>\n",
+              "      <td>43.978502</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 1, 0]</td>\n",
+              "      <td>15.539617</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>14</th>\n",
+              "      <td>4</td>\n",
+              "      <td>0.339753</td>\n",
+              "      <td>7.068189</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 1, 0]</td>\n",
+              "      <td>3.599934</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>15</th>\n",
+              "      <td>4</td>\n",
+              "      <td>0.727159</td>\n",
+              "      <td>1.449973</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 1, 0]</td>\n",
+              "      <td>1.013762</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>16</th>\n",
+              "      <td>5</td>\n",
+              "      <td>0.070874</td>\n",
+              "      <td>43.978502</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 1]</td>\n",
+              "      <td>15.539617</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>17</th>\n",
+              "      <td>5</td>\n",
+              "      <td>0.339753</td>\n",
+              "      <td>7.068189</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 1]</td>\n",
+              "      <td>3.599934</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>18</th>\n",
+              "      <td>5</td>\n",
+              "      <td>0.727159</td>\n",
+              "      <td>1.449973</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 1]</td>\n",
+              "      <td>1.013762</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>19</th>\n",
+              "      <td>6</td>\n",
+              "      <td>1.000000</td>\n",
+              "      <td>0.277432</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[1, 0, 0]</td>\n",
+              "      <td>0.270006</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>20</th>\n",
+              "      <td>7</td>\n",
+              "      <td>1.000000</td>\n",
+              "      <td>0.277432</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 1, 0]</td>\n",
+              "      <td>0.270006</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>21</th>\n",
+              "      <td>8</td>\n",
+              "      <td>1.000000</td>\n",
+              "      <td>0.277432</td>\n",
+              "      <td>[0.0, 0.0, 0.2201531]</td>\n",
+              "      <td>[0, 0, 1]</td>\n",
+              "      <td>0.270006</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>22</th>\n",
+              "      <td>9</td>\n",
+              "      <td>0.033495</td>\n",
+              "      <td>6.417017</td>\n",
+              "      <td>[0.0, 1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>18.731136</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>23</th>\n",
+              "      <td>9</td>\n",
+              "      <td>0.234727</td>\n",
+              "      <td>1.553171</td>\n",
+              "      <td>[0.0, 1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>2.825394</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>24</th>\n",
+              "      <td>9</td>\n",
+              "      <td>0.813757</td>\n",
+              "      <td>0.510043</td>\n",
+              "      <td>[0.0, 1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>0.640122</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>25</th>\n",
+              "      <td>10</td>\n",
+              "      <td>1.000000</td>\n",
+              "      <td>0.181381</td>\n",
+              "      <td>[0.0, 1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>0.161278</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>26</th>\n",
+              "      <td>11</td>\n",
+              "      <td>0.033495</td>\n",
+              "      <td>6.417017</td>\n",
+              "      <td>[0.0, -1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>18.731136</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>27</th>\n",
+              "      <td>11</td>\n",
+              "      <td>0.234727</td>\n",
+              "      <td>1.553171</td>\n",
+              "      <td>[0.0, -1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>2.825394</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>28</th>\n",
+              "      <td>11</td>\n",
+              "      <td>0.813757</td>\n",
+              "      <td>0.510043</td>\n",
+              "      <td>[0.0, -1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>0.640122</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>29</th>\n",
+              "      <td>12</td>\n",
+              "      <td>1.000000</td>\n",
+              "      <td>0.181381</td>\n",
+              "      <td>[0.0, -1.4539553, -0.8808013]</td>\n",
+              "      <td>[0, 0, 0]</td>\n",
+              "      <td>0.161278</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>"
+            ],
             "text/plain": [
               "  primitive    orbital    coefficient        norm  center                              lmn            alpha\n",
               "-----------  ---------  -------------  ----------  ----------------------------------  -------  -----------\n",
@@ -263,7 +575,7 @@
               "         29         12     1             0.181381  [ 0.        -1.4539553 -0.8808013]  [0 0 0]     0.161278"
             ]
           },
-          "execution_count": 4,
+          "execution_count": 3,
           "metadata": {},
           "output_type": "execute_result"
         }