fix_modify AtC mass_matrix command
fix_modify <AtC fixID> mass_matrix <fe|md_fe>
AtC fixID = ID of fix atc instance
mass_matrix = name of the AtC sub-command
fe or md_fe = activate/deactivate using the FE mass matrix in the MD region
fix_modify AtC mass_matrix fe
Determines whether AtC uses the FE mass matrix based on Gaussian quadrature or based on atomic quadrature in the MD region. This is useful for fully overlapping simulations to improve efficiency.
Should not be used unless the FE region is contained within the MD region, otherwise the method will be unstable and inaccurate.