<xsd:element name="atom" id="el.atom">
    <xsd:annotation>
        <xsd:documentation>
            <h:div class="summary" xmlns:h="http://www.w3.org/1999/xhtml">An atom.</h:div>
            <h:div documentation="general" xmlns:h="http://www.w3.org/1999/xhtml">Atoms can only be chosen from the periodic table and superatoms such as "Phe" or "Tyr" are not allowed. The elementType of an atom is identified by that attribute. There are two additional elementTypes, "Du" (for an object which does not have an identifiable nucleus but is useful in calculations and definitions (such as a centroid); and "R" which describes a generic fragment. Although atoms have an elementType, they do not, by default, support arbitrary atomTypes for which the &lt;atomType&gt; element should be used.</h:div>
            <h:div class="example" href="atom1.xml" xmlns:h="http://www.w3.org/1999/xhtml" />
            <h:div class="curation" xmlns:h="http://www.w3.org/1999/xhtml">2006-01-12: PMR. Added vector3 child to support
            accelerations, velocities, dipole, etc.</h:div>
            <h:div class="curation" xmlns:h="http://www.w3.org/1999/xhtml">2006-06-01: PMR. Added documentation.</h:div>
        </xsd:documentation>
        <xsd:appinfo />
    </xsd:annotation>
    <xsd:complexType>
        <xsd:choice>
            <xsd:choice minOccurs="0" maxOccurs="unbounded">
                <xsd:annotation>
                    <xsd:documentation>
                        <h:div class="general" xmlns:h="http://www.w3.org/1999/xhtml">
                            <h:p>The main content model of the atom.</h:p>
                            <h:ul>
                                <h:li>
                                    <h:b>name</h:b> can be used for atom labels, etc. More than one name can be used if required.</h:li>
                                <h:li>
                                    <h:b>scalar</h:b> contains any scalar properties of the atom (examples are chemical shift, B-value, etc.) linked through <h:tt>dictRef</h:tt> (CmlDictRefType).</h:li>
                                <h:li>
                                    <h:b>array</h:b> contains any  properties of the atom describable by a homogeneous array linked through <h:tt>dictRef</h:tt> (CmlDictRefType).</h:li>
                                <h:li>
                                    <h:b>matrix</h:b> contains any  properties of the atom describable by a homogeneous matrix linked through <h:tt>dictRef</h:tt> (CmlDictRefType). An example is the polarizability tensor</h:li>
                                <h:li>
                                    <h:b>atomParity</h:b> (CmlAtomParityElement) the required way of defining atom-based chirality</h:li>
                                <h:li>
                                    <h:b>electron</h:b> a away of associating electron(s) with the atom</h:li>
                            </h:ul>
                        </h:div>
                    </xsd:documentation>
                </xsd:annotation>
                <xsd:element ref="name" />
                <xsd:element ref="label" />
                <xsd:element ref="atomType" />
                <xsd:element ref="array" />
                <xsd:element ref="matrix" />
                <xsd:element ref="scalar" />
                <xsd:element ref="atomParity" />
                <xsd:element ref="electron" />
                <xsd:element ref="particle" />
                <xsd:element ref="vector3" />
            </xsd:choice>
        </xsd:choice>
        <xsd:attributeGroup ref="id" />
        <xsd:attributeGroup ref="convention" />
        <xsd:attributeGroup ref="dictRef" />
        <xsd:attributeGroup ref="ref" />
        <xsd:attributeGroup ref="count">
            <xsd:annotation>
                <xsd:documentation>
                    <h:div class="specific" xmlns:h="http://www.w3.org/1999/xhtml">Most useful in _formula_ but possibly useful in _atomArray_ where coordinates and connectivity is not defined. No formal default, but assumed to be 1.</h:div>
                </xsd:documentation>
            </xsd:annotation>
        </xsd:attributeGroup>
        <xsd:attributeGroup ref="elementType" />
        <xsd:attributeGroup ref="formalCharge" />
        <xsd:attributeGroup ref="hydrogenCount" />
        <xsd:attributeGroup ref="isotope" />
        <xsd:attributeGroup ref="isotopeNumber" />
        <xsd:attributeGroup ref="isotopeRef" />
        <xsd:attributeGroup ref="isotopeListRef" />
        <xsd:attributeGroup ref="occupancy" />
        <xsd:attributeGroup ref="spinMultiplicity" />
        <xsd:attributeGroup ref="x2" />
        <xsd:attributeGroup ref="y2" />
        <xsd:attributeGroup ref="x3" />
        <xsd:attributeGroup ref="y3" />
        <xsd:attributeGroup ref="z3" />
        <xsd:attributeGroup ref="xFract" />
        <xsd:attributeGroup ref="yFract" />
        <xsd:attributeGroup ref="zFract" />
        <xsd:attributeGroup ref="title" />
        <xsd:attributeGroup ref="role">
            <xsd:annotation>
                <xsd:documentation>
                    <h:div class="specific" xmlns:h="http://www.w3.org/1999/xhtml">This can be used to describe the purpose of atoms whose _elementType_s are __dummy__ or __locant__. Vocabulary not controlled.</h:div>
                </xsd:documentation>
            </xsd:annotation>
        </xsd:attributeGroup>
        <xsd:attributeGroup ref="spaceGroupMultiplicity">
            <xsd:annotation>
                <xsd:documentation>
                    <h:div class="curation" xmlns:h="http://www.w3.org/1999/xhtml">2005-11-27: Added PMR </h:div>
                </xsd:documentation>
            </xsd:annotation>
        </xsd:attributeGroup>
        <xsd:attributeGroup ref="pointGroupMultiplicity">
            <xsd:annotation>
                <xsd:documentation>
                    <h:div class="curation" xmlns:h="http://www.w3.org/1999/xhtml">2005-11-27: Added PMR </h:div>
                </xsd:documentation>
            </xsd:annotation>
        </xsd:attributeGroup>
    </xsd:complexType>
</xsd:element>