# BUCK4RANGES

Section can be repeated.

This section specifies the input parameters for the Buckingham 4-ranges potential type.

Range

Functional Form

$$r < r_1$$

$$V(r) = A\exp(-Br)$$

$$r_1 \leq r < r_2$$

$$V(r) = \sum_n \operatorname{POLY1}(n)r_n$$

$$r_2 \leq r < r_3$$

$$V(r) = \sum_n \operatorname{POLY2}(n)r_n$$

$$r \geq r_3$$

$$V(r) = -C/r_6$$

[Edit on GitHub]

## Keyword descriptions

A: real = [K_e]

Usage: A {real}

Defines the A parameter of the Buckingham potential [Edit on GitHub]

ATOMS: string[2]

Usage: ATOMS {KIND1} {KIND2}

Defines the atomic kind involved in the nonbond potential [Edit on GitHub]

B: real = [angstrom^-1]

Usage: B {real}

Defines the B parameter of the Buckingham potential [Edit on GitHub]

C: real = [angstrom^6*K_e]

Usage: C {real}

Defines the C parameter of the Buckingham potential [Edit on GitHub]

POLY1: real = [K_e]

Keyword can be repeated.

Usage: POLY1 C1 C2 C3 ..

Coefficients of the polynomial used in the second range This keyword can be repeated several times. [Edit on GitHub]

POLY2: real = [K_e]

Keyword can be repeated.

Usage: POLY1 C1 C2 C3 ..

Coefficients of the polynomial used in the third range This keyword can be repeated several times. [Edit on GitHub]

R1: real = [angstrom]

Usage: R1 {real}

Defines the upper bound of the first range [Edit on GitHub]

R2: real = [angstrom]

Usage: R2 {real}

Defines the upper bound of the second range [Edit on GitHub]

R3: real = [angstrom]

Usage: R3 {real}

Defines the upper bound of the third range [Edit on GitHub]

RCUT: real = 1.00000000E+001 [angstrom]

Usage: RCUT {real}

Defines the cutoff parameter of the Buckingham potential [Edit on GitHub]

RMAX: real = [angstrom]

Usage: RMAX {real}

Defines the upper bound of the potential. If not set the range is the full range generate by the spline [Edit on GitHub]

RMIN: real = [angstrom]

Usage: RMIN {real}

Defines the lower bound of the potential. If not set the range is the full range generate by the spline [Edit on GitHub]