c CCLRC
Section 5.1
Table 5.9: Valence Angle Potentials
key
potential type
Variables (1-4)
functional form
harm
Harmonic
k
0
U () =
k
2
( -
0
)
2
-hrm
quar
Quartic
k
0
k
k
U () =
k
2
( -
0
)
2
+
k
3
( -
0
)
3
+
k
4
( -
0
)
4
-qur
thrm
Truncated harmonic
k
0
U () =
k
2
( -
0
)
2
exp[-(r
8
ij
+ r
8
ik
)/
8
]
-thm
shrm
Screened harmonic
k
0
1
2
U () =
k
2
( -
0
)
2
exp[-(r
ij
/
1
+ r
ik
/
2
)]
-shm
bvs1
k
0
1
2
U () =
k
8(-
0
)
2
(
0
- )
2
- ( - )
2 2
×
-bv1
exp[-(r
ij
/
1
+ r
ik
/
2
)]
bvs2
k
0
a
U () = k[
a
( -
0
)
2
( +
0
- 2)
2
-
a
2
a-1
-bv2
( -
0
)
2
( -
0
)
3
] exp[-(r
8
ij
+ r
8
ik
)/
8
]
hcos
Harmonic Cosine
k
0
U () =
k
2
(cos() - cos(
0
))
2
-hcs
cos
Cosine
A
m
U () = A [1 + cos(m - )]
-cos
is the i-j-k angle
Note: valence angle potentials with a dash (-) as the first character of the keyword, do not
contribute to the excluded atoms list (see Section
). In this case DL POLY 3 will calculate the
non-bonded pair potentials between the described atoms.
93