1.. index:: angle_style cosine/delta 2.. index:: angle_style cosine/delta/omp 3 4angle_style cosine/delta command 5================================ 6 7Accelerator Variants: *cosine/delta/omp* 8 9Syntax 10"""""" 11 12.. code-block:: LAMMPS 13 14 angle_style cosine/delta 15 16Examples 17"""""""" 18 19.. code-block:: LAMMPS 20 21 angle_style cosine/delta 22 angle_coeff 2*4 75.0 100.0 23 24Description 25""""""""""" 26 27The *cosine/delta* angle style uses the potential 28 29.. math:: 30 31 E = K [1 - \cos(\theta - \theta_0)] 32 33where :math:`\theta_0` is the equilibrium value of the angle, and :math:`K` is a 34prefactor. Note that the usual 1/2 factor is included in :math:`K`. 35 36The following coefficients must be defined for each angle type via the 37:doc:`angle_coeff <angle_coeff>` command as in the example above, or in 38the data file or restart files read by the :doc:`read_data <read_data>` 39or :doc:`read_restart <read_restart>` commands: 40 41* :math:`K` (energy) 42* :math:`\theta_0` (degrees) 43 44:math:`\theta_0` is specified in degrees, but LAMMPS converts it to radians 45internally. 46 47---------- 48 49.. include:: accel_styles.rst 50 51---------- 52 53Restrictions 54"""""""""""" 55 56This angle style can only be used if LAMMPS was built with the 57EXTRA-MOLECULE package. See the :doc:`Build package <Build_package>` doc page 58for more info. 59 60Related commands 61"""""""""""""""" 62 63:doc:`angle_coeff <angle_coeff>`, :doc:`angle_style cosine/squared <angle_cosine_squared>` 64 65Default 66""""""" 67 68none 69