def secondOrderTrans(high_phase, low_phase, Tstr='Tnuc'):
    """
    Assemble a dictionary describing a second-order phase transition.
    """
    rdict = {}
    rdict[Tstr] = 0.5*(high_phase.T[0] + low_phase.T[-1])
    rdict['low_vev'] = rdict['high_vev'] = high_phase.X[0]
    rdict['low_phase'] = low_phase.key
    rdict['high_phase'] = high_phase.key
    rdict['action'] = 0.0
    rdict['instanton'] = None
    rdict['trantype'] = 2
    rdict['betaHn_GW'] = 0.0
    return rdict