calculate shear modulus at given pressure.
    not fully tested with mdaap.

    :param p: pressure
    :param v0: volume at reference condition
    :param g0: shear modulus at reference condition
    :param g0p: pressure derivative of shear modulus at reference condition
    :param k0: bulk modulus at reference condition
    :param k0p: pressure derivative of bulk modulus at reference condition
    :return: shear modulus at high pressure

def bm3_g(p, v0, g0, g0p, k0, k0p):
    """
    calculate shear modulus at given pressure.
    not fully tested with mdaap.

    :param p: pressure
    :param v0: volume at reference condition
    :param g0: shear modulus at reference condition
    :param g0p: pressure derivative of shear modulus at reference condition
    :param k0: bulk modulus at reference condition
    :param k0p: pressure derivative of bulk modulus at reference condition
    :return: shear modulus at high pressure
    """
    return cal_g_bm3(p, [g0, g0p], [v0, k0, k0p])