# SMILES

SMILES is a package for molecular integrals with Slater functions implemented by J. Fernandez Rico, R. Lopez, G. Ramirez, I. Ema, D. Zorrilla and K.Ishida. It combines several techniques for the evaluation of the different types of integrals, a summary of which can be found in J. Fernandez Rico, R. Lopez, G. Ramirez, I. Ema, J. Comput. Chem. **25**, 1987-1994 (2004) and J. Fernandez Rico, I. Ema, R. Lopez, G. Ramirez and K. Ishida, *SMILES: A package for molecular calculations with STO* in Recent Advances in Computational Chemistry. Molecular Integrals over Stater Orbitals, Telhat Ozdogan and Maria Belen Ruiz eds., ISBN …

This code is not included in binary versions of Molpro, and by default the code is not included when building from source code; one should use the `--enable-slater`

configure option to enable compilation of the code.

The SMILES module is invoked by the `intyp=’SLATER’`

card. Name for ancillary files generated by the package can be supplied by `SLFILES=`

*filename*. Default name is ’slscratch’.

Three-center two-electron integrals of types $(AB|AC)$ and $(AB|CD)$ are computed by means of Gaussian expansions (STO-nG). The default length of the expansions is 9 (STO-9G). However, integrals obtained with STO-9G expansions may have not sufficient accuracy for post-HF calculations, specially with high quality basis sets. In these cases, the length of the expansions can be changed setting the variable `NGSSTO=`

*number of gaussians*. Though a maximum of `NGSSTO=30`

is allowed, the lengths of the expansions actually available in the package depend on the $(n,l)$ quantum numbers. If an expansion not included is required, the program takes the largest currently available.

Program limitations: In the current version, a maximum of 511 basis functions is allowed, and contracted functions cannot be used.

## INTERNAL BASIS SETS

The following internal basis sets are available.

Internal basis sets in SMILES | ||||
---|---|---|---|---|

Basis set | H-He | Li-Be | B-Ne | Na-Ar |

VB1 | [3,1] | [5,1] | [5,3,1] | — |

CVB1 | [3,1] | [6,2] | [6,4,1] | — |

FVB1 | [3,2,1] | [5,3,1,1] | [5,4,2,1] | — |

ZVB1 | [3,1] | [4,3,1] | [4,3,1] | [6,5,1] |

VB2 | [4,2,1] | [6,2,1] | [6,4,2,1] | — |

CVB2 | [4,2,1] | [7,3,2] | [7,5,3,1] | — |

ZVB2 | [4,2,1] | [5,4,2,1] | [5,4,2,1] | [7,6,2,1] |

VB3 | [5,3,2,1] | [7,3,2,1] | [7,5,3,2,1] | — |

CVB3 | [5,3,2,1] | [8,4,3,2] | [8,6,4,3,1] | — |

ZVB3 | [5,3,2,1] | [6,5,3,2,1] | [6,5,3,2,1] | [8,7,3,2,1] |

## EXTERNAL BASIS SETS

External basis sets can be supplied in a file that must be located in the working directory. Each record will contain the following data (free format):

I N L EXP NG

where:

I: atom type index (integer)

N: principal quantum number (integer)

L: angular quantum number (integer)

EXP: exponent (double precision)

NG: number of gaussians for the $(AB|AC)$ and $(AB|CB)$ integrals (integer)

Atom type index is used to establish the correspondence between the basis functions and the centers (atoms). All records having the same value of I will define the basis set for all the atoms of the corresponding type.

Example:

For a calculation on the CO$_2$ molecule with the following geometry data:

Geometry={ 3 C1, 0.000000000000E+00, 0.000000000000E+00, 0.000000000000E+00 O2, 0.000000000000E+00, 0.000000000000E+00,-0.117963799946E+01 O3, 0.000000000000E+00, 0.000000000000E+00, 0.117963799946E+01 }

Clementi and Roetti’s Single Zeta basis set could be supplied in an external file like:

1 1 0 5.67263 12 1 2 0 1.60833 12 1 2 1 1.56788 12 2 1 0 7.65781 12 2 2 0 2.24588 12 2 2 1 2.22662 12

The first three records define the basis set for atoms of the first type (carbon in this example), and the following three, the basis set for atoms of the second type (oxygen).

NG is mandatory even in case of diatomics, though gaussian expansions will not be used, the value of NG being irrelevant in this case.

## Example

Example using internal basis set for H$_2$O.

- examples/slater.inp
if(.not.modul_slater) then exit end if geomtyp=zmat geometry={ o;h1,o,r;h2,o,r,h1,theta } r=0.96 ang theta=102 intyp='SLATER' basis=VB1 hf ccsd(t) multi mrci