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two small doc corrections from Andrew Jewett for pair style gauss and dihedral style spherical

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Axel Kohlmeyer
2017-05-12 23:27:58 -04:00
parent 06c151421c
commit c5db3ff401
2 changed files with 10 additions and 9 deletions
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17
doc/src/dihedral_spherical.txt
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@ -14,10 +14,10 @@ dihedral_style spherical :pre
[Examples:]
dihedral_coeff 1 1 286.1 1 124 1 1 90.0 0 1 90.0 0
dihedral_coeff 1 3 286.1 1 114 1 1 90 0 1 90.0 0 &
17.3 0 0.0 0 1 158 1 0 0.0 0 &
15.1 0 0.0 0 0 0.0 0 1 167.3 1 :pre
dihedral_coeff 1 1 286.1 1 124 1 1 90.0 0 1 90.0 0
dihedral_coeff 1 3 69.3 1 93.9 1 1 90 0 1 90 0 &
49.1 0 0.00 0 1 74.4 1 0 0.00 0 &
25.2 0 0.00 0 0 0.00 0 1 48.1 1
[Description:]
@ -35,13 +35,14 @@ the dihedral interaction even if it requires adding additional terms to
the expansion (as was done in the second example). A careful choice of
parameters can prevent singularities that occur with traditional
force-fields whenever theta1 or theta2 approach 0 or 180 degrees.
The last example above corresponds to an interaction with a single energy
minima located at phi=114, theta1=158, theta2=167.3 degrees, and it remains
minima located near phi=93.9, theta1=74.4, theta2=48.1 degrees, and it remains
numerically stable at all angles (phi, theta1, theta2). In this example,
the coefficients 17.3, and 15.1 can be physically interpreted as the
the coefficients 49.1, and 25.2 can be physically interpreted as the
harmonic spring constants for theta1 and theta2 around their minima.
The coefficient 286.1 is the harmonic spring constant for phi after
division by sin(158)*sin(167.3) (the minima positions for theta1 and theta2).
The coefficient 69.3 is the harmonic spring constant for phi after
division by sin(74.4)*sin(48.1) (the minima positions for theta1 and theta2).
The following coefficients must be defined for each dihedral type via the
"dihedral_coeff"_dihedral_coeff.html command as in the example above, or in

2
doc/src/pair_gauss.txt
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@ -128,7 +128,7 @@ The B parameter is converted to a distance (sigma), before mixing
afterwards (using B=sigma^2).
Negative A values are converted to positive A values (using abs(A))
before mixing, and converted back after mixing
(by multiplying by sign(Ai)*sign(Aj)).
(by multiplying by min(sign(Ai),sign(Aj))).
This way, if either particle is repulsive (if Ai<0 or Aj<0),
then the default interaction between both particles will be repulsive.