def char_replacement(list_smiles):
    """
    Replace the double characters into single character in a list of SMILES string.

    Parameters
    ----------
    list_smiles: list
        list of SMILES string describing a compound.

    Returns
    -------
    list
        list of SMILES with character replacement.
    """
    return [
        smile.replace("Cl", "L")
        .replace("Br", "R")
        .replace("Se", "E")
        .replace("Zn", "Z")
        .replace("Si", "T")
        .replace("@@", "$")
        for smile in list_smiles
    ]