https://dictionary.iucr.org/index.php?title=Heavy-atom_method&feed=atom&action=historyHeavy-atom method - Revision history2024-03-29T15:47:52ZRevision history for this page on the wikiMediaWiki 1.30.0https://dictionary.iucr.org/index.php?title=Heavy-atom_method&diff=4482&oldid=prevBrianMcMahon: Added German and Spanish translations (U. Mueller)2017-11-14T09:19:48Z<p>Added German and Spanish translations (U. Mueller)</p>
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<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><<del class="diffchange diffchange-inline">Font </del>color="blue">Méthode de l'atome lourd</<del class="diffchange diffchange-inline">Font</del>> (''Fr''). <<del class="diffchange diffchange-inline">Font </del>color="black">Metodo dell'atomo pesante</<del class="diffchange diffchange-inline">Font</del>> (''It''). <<del class="diffchange diffchange-inline">Font </del>color="purple">重原子法</<del class="diffchange diffchange-inline">Font</del>> (''Ja'').<del class="diffchange diffchange-inline"> </del></div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><<ins class="diffchange diffchange-inline">font </ins>color="blue">Méthode de l'atome lourd</<ins class="diffchange diffchange-inline">font</ins>> (''Fr''). <<ins class="diffchange diffchange-inline">font color="red">Schweratom-Methode</font> (''Ge''). <font </ins>color="black">Metodo dell'atomo pesante</<ins class="diffchange diffchange-inline">font</ins>> (''It''). <<ins class="diffchange diffchange-inline">font </ins>color="purple">重原子法</<ins class="diffchange diffchange-inline">font</ins>> (''Ja''). <ins class="diffchange diffchange-inline"><font color="green">Método del átomo pesado</font> (''Sp'').</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td></tr>
</table>BrianMcMahonhttps://dictionary.iucr.org/index.php?title=Heavy-atom_method&diff=4011&oldid=prevBrianMcMahon: Style edits to align with printed edition2017-05-15T13:55:36Z<p>Style edits to align with printed edition</p>
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<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><Font color="blue">Méthode de l'atome lourd</Font> (''Fr'')<del class="diffchange diffchange-inline">; </del><Font color="black">Metodo dell'atomo pesante</Font> (''It'')<del class="diffchange diffchange-inline">; </del><Font color="purple">重原子法</Font> (''Ja''). </div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><Font color="blue">Méthode de l'atome lourd</Font> (''Fr'')<ins class="diffchange diffchange-inline">. </ins><Font color="black">Metodo dell'atomo pesante</Font> (''It'')<ins class="diffchange diffchange-inline">. </ins><Font color="purple">重原子法</Font> (''Ja''). </div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td colspan="2"> </td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td></tr>
</table>BrianMcMahonhttps://dictionary.iucr.org/index.php?title=Heavy-atom_method&diff=3641&oldid=prevMassimoNespolo: languages2016-03-30T11:22:49Z<p>languages</p>
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<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><Font color="blue"> Méthode de l'atome lourd </Font> (''Fr'').</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><Font color="blue">Méthode de l'atome lourd</Font> (''Fr<ins class="diffchange diffchange-inline">''); <Font color="black">Metodo dell'atomo pesante</Font> (''It''); <Font color="purple">重原子法</Font> (''Ja</ins>'').<ins class="diffchange diffchange-inline"> </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td></tr>
</table>MassimoNespolohttps://dictionary.iucr.org/index.php?title=Heavy-atom_method&diff=2722&oldid=prevAndreAuthier at 05:24, 4 April 20082008-04-04T05:24:42Z<p></p>
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<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"><Font color="blue"> Méthode de l'atome lourd </Font> (''Fr'').</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
</table>AndreAuthierhttps://dictionary.iucr.org/index.php?title=Heavy-atom_method&diff=2719&oldid=prevBrianMcMahon at 11:06, 3 April 20082008-04-03T11:06:03Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The figure shows how the [[structure factor]] is derived by vector addition of the scattered waves from the different contributing atoms in the unit cell. Consider the case of an atom with a very much higher scattering factor than any of the others <del class="diffchange diffchange-inline">(</del><math><del class="diffchange diffchange-inline">f_{0} </del>>> \<del class="diffchange diffchange-inline">sum_{i} </del>f_i</math><del class="diffchange diffchange-inline">)</del>; it is clear that the total phase angle <math>\phi</math> will be small, and that the net phase of the structure factor differs very little from that of the heavy-atom component alone.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The figure shows how the [[structure factor]] is derived by vector addition of the scattered waves from the different contributing atoms in the unit cell. Consider the case of an atom with a very much higher scattering factor than any of the others <math><ins class="diffchange diffchange-inline">(\,\,f_0 </ins>>> \<ins class="diffchange diffchange-inline">sum_i </ins>f_i <ins class="diffchange diffchange-inline">\,\,)</ins></math>; it is clear that the total phase angle <math>\phi</math> will be small, and that the net phase of the structure factor differs very little from that of the heavy-atom component alone.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>If the positions of known heavy atoms can be determined in this way, then the Patterson</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>If the positions of known heavy atoms can be determined in this way, then the Patterson <ins class="diffchange diffchange-inline">map, which describes interatomic vectors, allows  nearby peaks to be assigned to other atoms in accordance with expected molecular geometry. These are then used in calculating phase angles for the next approximate electron density map.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">A practical limitation is that a heavy atom that dominates the vector distribution is also likely to dominate the X-ray scattering as a whole, and overwhelm diffraction peaks from less strongly scattering species.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">[[Category:Structure determination]]</ins></div></td></tr>
</table>BrianMcMahonhttps://dictionary.iucr.org/index.php?title=Heavy-atom_method&diff=2718&oldid=prevBrianMcMahon at 09:41, 3 April 20082008-04-03T09:41:27Z<p></p>
<p><b>New page</b></p><div>An application of [[Patterson methods]] in crystal [[structure determination]]. For a compound containing a heavy atom (''i.e.'' one with a significantly higher [[atomic scattering factor]] than the others present) the diffraction phases calculated from the position of the heavy atom are used to compute a first approximate [[electron density map]]. Further portions of the structure are recognisable as additional peaks in the map. Successive approximate electron density maps may then be calculated to solve the entire structure.<br />
<br />
== Discussion ==<br />
<br />
[[Image:sfac4.gif|right]]<br />
<br />
The figure shows how the [[structure factor]] is derived by vector addition of the scattered waves from the different contributing atoms in the unit cell. Consider the case of an atom with a very much higher scattering factor than any of the others (<math>f_{0} >> \sum_{i} f_i</math>); it is clear that the total phase angle <math>\phi</math> will be small, and that the net phase of the structure factor differs very little from that of the heavy-atom component alone.<br />
<br />
If the positions of known heavy atoms can be determined in this way, then the Patterson</div>BrianMcMahon