# BEND

Section can be repeated.

Specifies the bend potential of the MM system. [Edit on GitHub]

Subsections

- UB

## Keywords

- ATOMS

- CB

- K

- KBS12

- KBS32

- KIND

- KSS

- LEGENDRE

- R012

- R032

- THETA0

## Keyword descriptions

ATOMS: string[3]

  Usage: ATOMS {KIND1} {KIND2} {KIND3}

  Defines the atomic kinds involved in the bend. [Edit on GitHub]

CB: real = 0.00000000E+000 [rad^-1]

  Usage: CB {real}

  Defines the the cubic force constant of the bend [Edit on GitHub]

K: real = [rad^-2*hartree]

  Usage: K {real}

  Defines the force constant of the potential [Edit on GitHub]

KBS12: real = 0.00000000E+000 [rad^-1*bohr^-1*hartree]

  Usage: KBS12 {real}

  Mixed bend stretch parameter [Edit on GitHub]

KBS32: real = 0.00000000E+000 [rad^-1*bohr^-1*hartree]

  Usage: KBS32 {real}

  Mixed bend stretch parameter [Edit on GitHub]

KIND: enum = CHARMM

  Usage: KIND HARMONIC

  Valid values:

  - `HARMONIC` Functional Form (HARMONIC|G87): 1/2K(THETA-THETA0)^2

  - `CHARMM` Functional Form (CHARMM|AMBER): K*(THETA-THETA0)^2

  - `AMBER` Functional Form (CHARMM|AMBER): K*(THETA-THETA0)^2

  - `G87` Functional Form (HARMONIC|G87): 1/2K(THETA-THETA0)^2

  - `G96` Functional Form (G96): 1/2K(COS(THETA)-THETA0)^2

  - `CUBIC` Functional Form (CUBIC): K*(THETA-THETA0)2(1+CB(THETA-THETA0))

  - `MIXED_BEND_STRETCH` Functional Form (MIXED_BEND_STRETCH): K*(THETA-THETA0)2(1+CB(THETA-THETA0))+ KSS*(R12-R012)(R32-R032)+KBS12(R12-R012)(THETA-THETA0)+KBS32(R32-R032)*(THETA-THETA0)

  - `MM3` Functional Form (MM3): 1/2K(THETA-THETA0)2(1-0.014(THETA-THETA0)+5.6E-5*(THETA-THETA0)*2 -7.0E-7(THETA-THETA0)*3+9.0E-10(THETA-THETA0)*4)+KBS12(R12-R012)(THETA-THETA0)+ KBS32(R32-R032)*(THETA-THETA0)

  - `LEGENDRE` Functional Form (LEGENDRE): sum_{i=0}^N c_i*P_i(COS(THETA))

  Define the kind of bend potential [Edit on GitHub]

KSS: real = 0.00000000E+000 [bohr^-2*hartree]

  Usage: KSS {real}

  Mixed bend stretch parameter [Edit on GitHub]

LEGENDRE: real[ ] = 0.00000000E+000 [hartree]

  Usage: LEGENDRE {REAL} {REAL} …

  Specifies the coefficients for the legendre expansion of the bending potential. ‘THETA0’ and ‘K’ are not used, but need to be specified. Use an arbitrary value. [Edit on GitHub]

R012: real = 0.00000000E+000 [bohr]

  Usage: R012 {real}

  Mixed bend stretch parameter [Edit on GitHub]

R032: real = 0.00000000E+000 [bohr]

  Usage: R032 {real}

  Mixed bend stretch parameter [Edit on GitHub]

THETA0: real = [rad]

  Usage: THETA0 {real}

  Defines the equilibrium angle. [Edit on GitHub]