1.. index:: fix_modify AtC control momentum 2 3fix_modify AtC control momentum command 4======================================= 5 6Syntax 7"""""" 8 9.. parsed-literal:: 10 11 fix_modify <AtC fixID> control <physics_type> <solution_parameter> <value> 12 fix_modify AtC control momentum none 13 fix_modify AtC control momentum rescale <frequency> 14 fix_modify AtC control momentum glc_displacement 15 fix_modify AtC control momentum glc_velocity 16 fix_modify AtC control momentum hoover 17 fix_modify AtC control momentum flux [faceset face_set_id, interpolate] 18 19* AtC fixID = ID of :doc:`fix atc <fix_atc>` instance 20* control = name of the AtC sub-command 21* physics_type = *thermal* or *momentum* 22* solution_parameter = *max_iterations* or *tolerance* 23* value = solution_parameter value 24* momentum option = *none* or *rescale* or *glc_displacement* or *glc_velocity* *hoover* or *flux* 25* frequency = time step frequency for applying displacement and velocity rescaling 26* faceset_id = id of boundary face set (optional, only for *faceset*) 27 28 29Examples 30"""""""" 31 32.. code-block:: LAMMPS 33 34 fix_modify AtC control momentum none 35 fix_modify AtC control momentum flux faceset bndy_faces 36 fix_modify AtC control momentum glc_velocity 37 38Description 39""""""""""" 40 41The general version of *control* sets the numerical parameters for the 42matrix solvers used in the specified control algorithm. Many solution 43approaches require iterative solvers, and these methods enable users to 44provide the maximum number of iterations and the relative tolerance. 45 46The *control momentum* version sets the momentum exchange mechanism from 47the finite elements to the atoms, managed through a control algorithm. 48*rescale* computes a scale factor for each atom to match the finite 49element temperature. *hoover* is a Gaussian least-constraint isokinetic 50thermostat enforces that the nodal restricted atomic temperature matches 51the finite element temperature. *flux* is a similar mode, but rather 52adds energy to the atoms based on conservation of energy. 53 54*correction_max_iterations* sets the maximum number of iterations to 55compute the second order in time correction term for lambda with the 56fractional step method. The method uses the same tolerance as the 57controller's matrix solver. 58 59Restrictions 60"""""""""""" 61 62Only for be used with the specific controllers *thermal* or *momentum*. 63They are ignored if a lumped solution is requested. 64 65*control momentum* is only for be used with specific transfers: elastic 66*rescale* not valid with time filtering activated 67 68Related AtC commands 69"""""""""""""""""""" 70 71- :ref:`fix_modify AtC command overview <atc_fix_modify>` 72- :doc:`fix_modify AtC control thermal <atc_control_thermal>` 73 74Default 75""""""" 76 77- *max_iterations* is the number of rows in the matrix. 78- *tolerance* is 1.0e-10. 79