# SIEPMANN

Section can be repeated.

References: Siepmann1995

This section specifies the input parameters for the Siepmann-Sprik potential type. Consists of 4 terms: T1+T2+T3+T4. The terms T1=A/rij^alpha and T2=-C/rij^6 have to be given via the GENPOT section. The terms T3+T4 are obtained from the SIEPMANN section. The Siepmann-Sprik potential is designed for water-metal chemisorption. [Edit on GitHub]

## Keywords

- ALLOW_H3O_FORMATION

- ALLOW_OH_FORMATION

- ALLOW_O_FORMATION

- ATOMS

- B

- BETA

- D

- E

- F

- RCUT

## Keyword descriptions

ALLOW_H3O_FORMATION: logical = F

  Lone keyword: `T`

  Usage: ALLOW_H3O_FORMATION TRUE

  The Siepmann-Sprik potential is designed for intact water molecules only. If water is treated at the QM level and an acid is present, hydronium ions might occur. This keyword allows the formation of hydronium ions. The T3 term (dipole term) is switched off for evaluating the interaction between hydronium and the metal. [Edit on GitHub]

ALLOW_OH_FORMATION: logical = F

  Lone keyword: `T`

  Usage: ALLOW_OH_FORMATION TRUE

  The Siepmann-Sprik potential is actually designed for intact water molecules only. If water is treated at the QM level, water molecules can potentially dissociate, i.e. some O-H bonds might be stretched leading temporarily to the formation of OH- ions. This keyword allows the the formation of such ions. The T3 term (dipole term) is then switched off for evaluating the interaction between the OH- ion and the metal. [Edit on GitHub]

ALLOW_O_FORMATION: logical = F

  Lone keyword: `T`

  Usage: ALLOW_O_FORMATION .TRUE.

  The Siepmann-Sprik potential is actually designed for intact water molecules only. If water is treated at the QM level, water molecules can potentially dissociate, i.e. some O-H bonds might be stretched leading temporarily to the formation of O^2- ions. This keyword allows the the formation of such ions. The T3 term (dipole term) is then switched off for evaluating the interaction between the O^2- ion and the metal. [Edit on GitHub]

ATOMS: string[2]

  Usage: ATOMS {KIND1} {KIND2}

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

B: real = 6.00000000E-001 [angstrom]

  Usage: B {real}

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

BETA: real = 1.00000000E+001

  Usage: beta {real}

  Defines the beta parameter of Siepmann potential [Edit on GitHub]

D: real = 3.68838800E+000 [internal_cp2k]

  Usage: D {real}

  Defines the D parameter of Siepmann potential [Edit on GitHub]

E: real = 9.06902500E+000 [internal_cp2k]

  Usage: E {real}

  Defines the E parameter of Siepmann potential [Edit on GitHub]

F: real = 1.33000000E+001

  Usage: F {real}

  Defines the F parameter of Siepmann potential [Edit on GitHub]

RCUT: real = 3.20000000E+000 [angstrom]

  Usage: RCUT {real}

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