remove some unneeded backslash escapes

Additional to the cosine term the *cosine/buck6d* angle style computes

the short range (vdW) interaction belonging to the

:doc:`pair\_buck6d <pair_buck6d_coul_gauss>` between the end atoms of the

:doc:`pair_style buck6d <pair_buck6d_coul_gauss>` between the end atoms of the

angle.  For this reason this angle style only works in combination

with the :doc:`pair\_buck6d <pair_buck6d_coul_gauss>` styles and needs

with the :doc:`pair_style buck6d <pair_buck6d_coul_gauss>` styles and needs

the :doc:`special_bonds <special_bonds>` 1-3 interactions to be weighted

0.0 to prevent double counting.

*cosine/buck6d* can only be used in combination with the

:doc:`pair\_buck6d <pair_buck6d_coul_gauss>` style and with a

:doc:`pair_style buck6d <pair_buck6d_coul_gauss>` style and with a

:doc:`special_bonds <special_bonds>` 0.0 weighting of 1-3 interactions.

This angle style can only be used if LAMMPS was built with the

""""""""""""""""

:doc:`angle_coeff <angle_coeff>`,

:doc:`angle\_cosine\_shift\_exp <angle_cosine_shift_exp>`

:doc:`angle_style cosine/shift/exp <angle_cosine_shift_exp>`

**Default:** none

""""""""""""""""

:doc:`angle_coeff <angle_coeff>`,

:doc:`angle\_cosine\_shift <angle_cosine_shift>`,

:doc:`dihedral\_cosine\_shift\_exp <dihedral_cosine_shift_exp>`

:doc:`angle_style cosine/shift <angle_cosine_shift>`,

:doc:`dihedral_style cosine/shift/exp <dihedral_cosine_shift_exp>`

**Default:** none

:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`,

:doc:`bond_harmonic <bond_harmonic>`,

:doc:`bond\_harmonic\_shift <bond_harmonic_shift>`

:doc:`bond_style harmonic/shift <bond_harmonic_shift>`

**Default:** none

""""""""""""""""

:doc:`fix adapt/fep <fix_adapt_fep>`, :doc:`fix ave/time <fix_ave_time>`,

:doc:`pair\_fep\_soft <pair_fep_soft>`

:doc:`pair_style .../soft <pair_fep_soft>`

Default

"""""""