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correct and clarify statements about the potentials and their relations to each other

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Axel Kohlmeyer
2025-03-10 06:26:37 -04:00
parent 79d2346eaa
commit 312bdcbddd
3 changed files with 21 additions and 9 deletions
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2
doc/src/bond_harmonic.rst
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@ -60,6 +60,8 @@ Related commands
""""""""""""""""
:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`
:doc:`bond style harmonic/shift <bond_harmonic_shift>`,
:doc:`bond style harmonic/shift/cut <bond_harmonic_shift_cut>`
Default
"""""""

17
doc/src/bond_harmonic_shift.rst
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@ -31,9 +31,15 @@ the potential
E = \frac{U_{\text{min}}}{(r_0-r_c)^2} \left[ (r-r_0)^2-(r_c-r_0)^2 \right]
where :math:`r_0` is the equilibrium bond distance, and :math:`r_c` the critical distance.
The potential is :math:`-U_{\text{min}}` at :math:`r0` and zero at :math:`r_c`. The spring constant is
:math:`k = U_{\text{min}} / [ 2 (r_0-r_c)^2]`.
where :math:`r_0` is the equilibrium bond distance, and :math:`r_c` the
critical distance. The potential energy has the value
:math:`-U_{\text{min}}` at :math:`r_0` and zero at :math:`r_c`. This
bond style differs from :doc:`bond_style harmonic <bond_harmonic>`
by the value of the potential energy.
The equivalent spring constant value *K* for use with :doc:`bond_style
harmonic <bond_harmonic>` can be computed using :math:`K =
U_{\text{min}} / [(r_0-r_c)^2]`.
The following coefficients must be defined for each bond type via the
:doc:`bond_coeff <bond_coeff>` command as in the example above, or in
@ -41,9 +47,7 @@ the data file or restart files read by the :doc:`read_data <read_data>`
or :doc:`read_restart <read_restart>` commands:
* :math:`U_{\text{min}}` (energy)
* :math:`r_0` (distance)
* :math:`r_c` (distance)
----------
@ -63,7 +67,8 @@ Related commands
""""""""""""""""
:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`,
:doc:`bond_harmonic <bond_harmonic>`
:doc:`bond style harmonic <bond_harmonic>`,
:doc:`bond style harmonic/shift/cut <bond_harmonic_shift_cut>`
Default
"""""""

11
doc/src/bond_harmonic_shift_cut.rst
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@ -31,9 +31,14 @@ uses the potential
E = \frac{U_{\text{min}}}{(r_0-r_c)^2} \left[ (r-r_0)^2-(r_c-r_0)^2 \right]
where :math:`r_0` is the equilibrium bond distance, and rc the critical distance.
The bond potential is zero for distances :math:`r > r_c`. The potential is :math:`-U_{\text{min}}`
at :math:`r_0` and zero at :math:`r_c`. The spring constant is :math:`k = U_{\text{min}} / [ 2 (r_0-r_c)^2]`.
where :math:`r_0` is the equilibrium bond distance, and :math:`r_c` the
critical distance. The bond potential is zero and thus its force also
zero for distances :math:`r > r_c`. The potential energy has the value
:math:`-U_{\text{min}}` at :math:`r_0` and zero at :math:`r_c`.
The equivalent spring constant value *K* for use with :doc:`bond_style
harmonic <bond_harmonic>` for :math:`r <= r_c`, can be computed using
:math:`K = U_{\text{min}} / [(r_0-r_c)^2]`
The following coefficients must be defined for each bond type via the
:doc:`bond_coeff <bond_coeff>` command as in the example above, or in