Editing Atomic units (section)

=== Explicit units ===
* Many texts (e.g. Jerrard & McNiell,<ref name="JerrardMcNeill1992"/> Shull & Hall<ref name="ShullHall1959"/>) define the atomic units as quantities, without a transformation of the equations in use.  As such, they do not suggest treating either quantities as dimensionless or changing the form of any equations.  This is consistent with expressing quantities in terms of dimensional quantities, where the atomic unit is included explicitly as a symbol (e.g. {{tmath|1= m = 3.4~m_\text{e} }}, {{tmath|1= m = 3.4~\text{a.u. of mass} }}, or more ambiguously, {{tmath|1= m = 3.4~\text{a.u.} }}), and keeping equations unaltered with explicit constants.<ref name="Pilar2001">{{cite book |last=Pilar |first=Frank L. |title=Elementary Quantum Chemistry |year=2001 |publisher=Dover Publications |isbn=978-0-486-41464-5 |page=155 |url=https://books.google.com/books?id=XpGM7r69LdkC&pg=PA155 }}</ref>
* Provision for choosing more convenient closely related quantities that are more suited to the problem as units than universal fixed units are is also suggested, for example based on the [[reduced mass]] of an electron, albeit with careful definition thereof where used (for example, a unit {{tmath|1= H_M = \mu e^4 / \hbar^2}}, where {{tmath|1= \mu = m_\text{e} M / (m_\text{e} + M) }} for a specified mass {{tmath|1= M }}).<ref name="ShullHall1959"/>