Specifies whether or not the value for Alpha in the Ewald method is to be determined
automatically or specified manually.

<p>
If <tt>Ewald_option_Alpha = 0</tt>, then <tt>Ewald_Alpha</tt> is determined automatically, and
<tt>Ewald_Rcut = Ewald_precision / Ewald_Alpha</tt>.

<p>
If <tt>Ewald_option_Alpha = 1</tt>, then <tt>Ewald_precision</tt> and <tt>Ewald_Rcut</tt>
are specified manually, and 
<tt>Ewald_Alpha = Ewald_precision / Ewald_Rcut</tt>.

