diff --git a/doc/src/Eqs/angle_harmonic.jpg b/doc/src/Eqs/angle_harmonic.jpg
deleted file mode 100644
index 352be0b544..0000000000
Binary files a/doc/src/Eqs/angle_harmonic.jpg and /dev/null differ
diff --git a/doc/src/Eqs/angle_harmonic.tex b/doc/src/Eqs/angle_harmonic.tex
deleted file mode 100644
index c566376b5b..0000000000
--- a/doc/src/Eqs/angle_harmonic.tex
+++ /dev/null
@@ -1,9 +0,0 @@
-\documentclass[12pt]{article}
-
-\begin{document}
-
-$$
-  E = K (\theta - \theta_0)^2 
-$$
-
-\end{document}
\ No newline at end of file
diff --git a/doc/src/angle_harmonic.rst b/doc/src/angle_harmonic.rst
index 87b71ad9ad..1066621729 100644
--- a/doc/src/angle_harmonic.rst
+++ b/doc/src/angle_harmonic.rst
@@ -1,22 +1,22 @@
-.. index:: angle\_style harmonic
+.. index:: angle_style harmonic
 
-angle\_style harmonic command
-=============================
+angle_style harmonic command
+============================
 
-angle\_style harmonic/intel command
-===================================
+angle_style harmonic/intel command
+==================================
 
-angle\_style harmonic/kk command
+angle_style harmonic/kk command
+===============================
+
+angle_style harmonic/omp command
 ================================
 
-angle\_style harmonic/omp command
-=================================
-
 Syntax
 """"""
 
 
-.. parsed-literal::
+.. code-block:: LAMMPS
 
    angle_style harmonic
 
@@ -24,7 +24,7 @@ Examples
 """"""""
 
 
-.. parsed-literal::
+.. code-block:: LAMMPS
 
    angle_style harmonic
    angle_coeff 1 300.0 107.0
@@ -34,22 +34,24 @@ Description
 
 The *harmonic* angle style uses the potential
 
-.. image:: Eqs/angle_harmonic.jpg
-   :align: center
+.. math::
 
-where theta0 is the equilibrium value of the angle, and K is a
-prefactor.  Note that the usual 1/2 factor is included in K.
+   E = K (\theta - \theta_0)^2
+
+
+where :math:`\theta_0` is the equilibrium value of the angle, and :math:`K` is a
+prefactor.  Note that the usual 1/2 factor is included in :math:`K`.
 
 The following coefficients must be defined for each angle type via the
 :doc:`angle\_coeff <angle_coeff>` command as in the example above, or in
 the data file or restart files read by the :doc:`read\_data <read_data>`
 or :doc:`read\_restart <read_restart>` commands:
 
-* K (energy/radian\^2)
-* theta0 (degrees)
+* :math:`K` (energy/radian\^2)
+* :math:`\theta_0` (degrees)
 
-Theta0 is specified in degrees, but LAMMPS converts it to radians
-internally; hence the units of K are in energy/radian\^2.
+:math:`\theta_0` is specified in degrees, but LAMMPS converts it to radians
+internally; hence the units of :math:`K` are in energy/radian\^2.
 
 
 ----------
@@ -91,8 +93,3 @@ Related commands
 :doc:`angle\_coeff <angle_coeff>`
 
 **Default:** none
-
-
-.. _lws: http://lammps.sandia.gov
-.. _ld: Manual.html
-.. _lc: Commands_all.html
diff --git a/doc/txt/angle_harmonic.txt b/doc/txt/angle_harmonic.txt
deleted file mode 100644
index b632f68478..0000000000
--- a/doc/txt/angle_harmonic.txt
+++ /dev/null
@@ -1,77 +0,0 @@
-"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
-
-:link(lws,http://lammps.sandia.gov)
-:link(ld,Manual.html)
-:link(lc,Commands_all.html)
-
-:line
-
-angle_style harmonic command :h3
-angle_style harmonic/intel command :h3
-angle_style harmonic/kk command :h3
-angle_style harmonic/omp command :h3
-
-[Syntax:]
-
-angle_style harmonic :pre
-
-[Examples:]
-
-angle_style harmonic
-angle_coeff 1 300.0 107.0 :pre
-
-[Description:]
-
-The {harmonic} angle style uses the potential
-
-:c,image(Eqs/angle_harmonic.jpg)
-
-where theta0 is the equilibrium value of the angle, and K is a
-prefactor.  Note that the usual 1/2 factor is included in K.
-
-The following coefficients must be defined for each angle type via the
-"angle_coeff"_angle_coeff.html command as in the example above, or in
-the data file or restart files read by the "read_data"_read_data.html
-or "read_restart"_read_restart.html commands:
-
-K (energy/radian^2)
-theta0 (degrees) :ul
-
-Theta0 is specified in degrees, but LAMMPS converts it to radians
-internally; hence the units of K are in energy/radian^2.
-
-:line
-
-Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
-functionally the same as the corresponding style without the suffix.
-They have been optimized to run faster, depending on your available
-hardware, as discussed on the "Speed packages"_Speed_packages.html doc
-page.  The accelerated styles take the same arguments and should
-produce the same results, except for round-off and precision issues.
-
-These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
-USER-OMP and OPT packages, respectively.  They are only enabled if
-LAMMPS was built with those packages.  See the "Build
-package"_Build_package.html doc page for more info.
-
-You can specify the accelerated styles explicitly in your input script
-by including their suffix, or you can use the "-suffix command-line
-switch"_Run_options.html when you invoke LAMMPS, or you can use the
-"suffix"_suffix.html command in your input script.
-
-See the "Speed packages"_Speed_packages.html doc page for more
-instructions on how to use the accelerated styles effectively.
-
-:line
-
-[Restrictions:]
-
-This angle style can only be used if LAMMPS was built with the
-MOLECULE package.  See the "Build package"_Build_package.html doc
-page for more info.
-
-[Related commands:]
-
-"angle_coeff"_angle_coeff.html
-
-[Default:] none