calculate bulk modulus in GPa

    :param p: pressure in GPa
    :param k: [v0, k0, k0p]
    :return: bulk modulus at high pressure in GPa

def cal_k_vinet(p, k):
    """
    calculate bulk modulus in GPa

    :param p: pressure in GPa
    :param k: [v0, k0, k0p]
    :return: bulk modulus at high pressure in GPa
    """
    v = cal_v_vinet(p, k)
    return cal_k_vinet_from_v(v, k[0], k[1], k[2])