BUCK4RANGES

Section can be repeated.

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

Range	Functional Form
\( r < r_1 \)	\( V(r) = A\exp(-Br) \)
\( r_1 \leq r < r_2 \)	\( V(r) = \sum_n \operatorname{POLY1}(n)r_n \)
\( r_2 \leq r < r_3 \)	\( V(r) = \sum_n \operatorname{POLY2}(n)r_n \)
\( r \geq r_3 \)	\( V(r) = -C/r_6 \)

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Keywords

• A

• ATOMS

• B

• C

• POLY1

• POLY2

• R1

• R2

• R3

• RCUT

• RMAX

• RMIN

Keyword descriptions

A

Type: real
Default: [K_e]
Usage: A {real}

Description: Defines the A parameter of the Buckingham potential

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ATOMS

Type: string[2]
Usage: ATOMS {KIND1} {KIND2}

Description: Defines the atomic kind involved in the nonbond potential

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B

Type: real
Default: [angstrom^-1]
Usage: B {real}

Description: Defines the B parameter of the Buckingham potential

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C

Type: real
Default: [angstrom^6*K_e]
Usage: C {real}

Description: Defines the C parameter of the Buckingham potential

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POLY1

Type: real[ ]
Default: [K_e]
Repeatable: yes
Usage: POLY1 C1 C2 C3 ..

Description: Coefficients of the polynomial used in the second range This keyword can be repeated several times.

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POLY2

Type: real[ ]
Default: [K_e]
Repeatable: yes
Usage: POLY2 C1 C2 C3 ..

Description: Coefficients of the polynomial used in the third range This keyword can be repeated several times.

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R1

Type: real
Default: [angstrom]
Usage: R1 {real}

Description: Defines the upper bound of the first range

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R2

Type: real
Default: [angstrom]
Usage: R2 {real}

Description: Defines the upper bound of the second range

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R3

Type: real
Default: [angstrom]
Usage: R3 {real}

Description: Defines the upper bound of the third range

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RCUT

Type: real
Default: 1.00000000E+001 [angstrom]
Usage: RCUT {real}

Description: Defines the cutoff parameter of the Buckingham potential

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RMAX

Type: real
Default: [angstrom]
Usage: RMAX {real}

Description: Defines the upper bound of the potential. If not set the range is the full range generate by the spline

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RMIN

Type: real
Default: [angstrom]
Usage: RMIN {real}

Description: Defines the lower bound of the potential. If not set the range is the full range generate by the spline

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