Editing Input syntax manual (section)

=== set cmm ===

 '''set cmm''' ''OPT''
Sets calculation of diffusion coefficients using the cumulative migration method (CMM) on or off. Input values:

{|
| <tt>''OPT''</tt>
| : option to switch CMM calculation on (1/yes) or off (0/no)
|}

<u>Notes:</u>

*Methodology:
**The CMM diffusion coefficients and transport cross sections are reasonable only when they are calculated over entire geometry:
***The homogenized region covers the entire geometry and is surrounded by periodic or reflective boundary conditions.
***This means that e.g. pin cell diffusion coefficients can not be calculated from a 2D fuel assembly calculation. 
**The CMM methodology was revised in version 2.1.31 so that the calculated values may be different than with previous versions.
**One may try to approximate the CMM estimates with the transport correction for hydrogen for light water reactor applications (see [[#set trc|set trc]] option).
*Setup:
**CMM diffusion coefficients and transport cross sections  can be calculated also when using implicit capture reactions (see [[#set_impl|set impl]] option),  from version 2.1.31 and on.
**The calculation of CMM estimates (diffusion coefficients and transport cross sections) might take considerable time. Switch "<tt>off</tt>" the evaluation if the data is not needed.
**The use of private results array may be recommended when calculating CMM estimates (see [[#set_shbuf|set shbuf]] option).
*The CMM diffusion coefficients <tt>CMM_DIFFCOEF</tt> and transport cross sections <tt>CMM_TRANSPXS</tt> estimates are written in:
** <tt>[input]_res.m</tt> output file: [[Output parameters#Homogenized group constants|homogenized group constants]] section - diffusion parameters: for infinite spectrum and critical spectrum.
** <tt>[input].coe</tt> ouput file, via the [[Input syntax manual#set_coefpara|set coefpara]] option: [[Automated_burnup_sequence#Output|automated burnup sequence/coefficient matrix]] output.
*The cumulative migration method (CMM) is described in related papers<ref>Liu, Z., Smith, K., Forget, B. and Ortensi, J. ''"Cumulative migration method for computing rigorous diffusion coefficients and transport cross sections from Monte Carlo."'' Ann. Nuc. Energy, [https://doi.org/10.1016/j.anucene.2017.10.039 '''112''' (2016) 126-136]</ref><ref>Liu, Z., Smith, K. and Forget, B. ''"Group-wise Tally Scheme of Incremental Migration Area for Cumulative Migration Method."'' In proc. PHYSOR 2018, Cancun, Mexico, Apr. 22-26, 2018</ref>.