1*  \\\\\\\ United Atom Butane Parameters (Charmm "extened" model) ///////
2*  \\\\\\\  most recent update Tues April 5th by Paul R Brenner  ////////
3*  \\ based on data from Barth, LeimKuhler, and Reich 2002 Charmm19 ////
4*  \ dihedral energy according to Izaguirre and Hampton 2004 Charmm19 /
5
6BONDS
7!
8!V(bond) = Kb(b - b0)**2
9!
10!Kb: kcal/mole/A**2
11!b0: A
12!
13!atom type Kb          b0
14!
15
16CH2   CH2   225.000     1.520   ! from CHARMM version 19
17CH2   CH3   225.000     1.540   ! from CHARMM version 19
18
19
20ANGLES
21!
22!V(angle) = Ktheta(Theta - Theta0)**2
23!
24!V(Urey-Bradley) = Kub(S - S0)**2
25!
26!Ktheta: kcal/mole/rad**2
27!Theta0: degrees
28!Kub: kcal/mole/A**2 (Urey-Bradley)
29!S0: A
30!
31!atom types     Ktheta    Theta0   Kub     S0
32!
33
34CH3  CH2  CH2    45.00     110.00   ! United Atom Butane
35
36
37DIHEDRALS
38!
39!V(dihedral) = Kchi(1 + cos(n(chi) - delta))
40!
41!Kchi: kcal/mole
42!n: multiplicity
43!delta: degrees
44!
45!atom types             Kchi    n   delta
46!
47
48CH3  CH2  CH2  CH3      1.6000  3     0.00 ! United atom butane
49CH3  CH2  CH2  CH3      0.6     1     0.00 ! United Atom butane
50
51
52NONBONDED nbxmod  5 atom cdiel fshift vatom vdistance vfswitch -
53!cutnb 14.0 ctofnb 12.0 ctonnb 10.0 eps 1.0 e14fac 1.0 wmin 1.5
54!
55!V(Lennard-Jones) = Eps,i,j[(Rmin,i,j/ri,j)**12 - 2(Rmin,i,j/ri,j)**6]
56!
57!epsilon: kcal/mole, Eps,i,j = sqrt(eps,i * eps,j)
58!Rmin/2: A, Rmin,i,j = Rmin/2,i + Rmin/2,j
59!
60!atom  ignored    epsilon     Rmin/2   ignored   eps,1-4       Rmin/2,1-4
61!
62CH2      0.0       -0.1142    2.235 ! UA butane
63CH3      0.0       -0.1811    2.165 ! UA butane
64
65
66NBFIX
67!               Emin        Rmin
68!            (kcal/mol)     (A)
69!
70
71HBOND CUTHB 0.5  ! If you want to do hbond analysis (only), then use
72                 ! READ PARAM APPEND CARD
73                 ! to append hbond parameters from the file: par_hbond.inp
74
75END
76