- face_set_id (string), optional = id of boundary face set, if not specified
(or not possible when the atomic domain does not line up with
mesh boundaries) defaults to an atomic-quadrature approximate
evaulation, does not work with interpolate\n
\section examples
<TT> fix_modify AtC transfer thermal control none </TT> \n
<TT> fix_modify AtC transfer thermal control rescale 10 </TT> \n
<TT> fix_modify AtC transfer thermal control hoover </TT> \n
<TT> fix_modify AtC transfer thermal control flux bndy_faces </TT> \n
\section description
Sets the energy exchange mechansim from the finite elements to the atoms, managed through a control algorithm. Rescale computes a scale factor for each atom to match the finite element temperature. Hoover is a Gaussian least-constraint isokinetic thermostat enforces that the nodal restricted atomic temperature matches the finite element temperature. Flux is a similar mode, but rather adds energy to the atoms based on conservation of energy. Hoover and flux allows the prescription of sources or fixed temperatures on the atoms.