“…Most implicit methods proposed since the 1970s are designed to have second-order accuracy, unconditional stability and tunable algorithmic dissipation in the linear regime, including the single-step single-solve methods [6,11,36,45], the linear multi-step methods [26,27,43], and the composite multi-sub-step methods [5,9,13,16,18,23,29,40,44]. The single-step singlesolve methods, such as the HHT-α method [11] proposed by Hilber, Hughes and Taylor, the generalized-α method [6,31,41], as well as the linear multi-step methods (see for example [43]) are limited by Dahlquist's barrier [8], which states that methods of higher than second-order accuracy cannot achieve unconditional stability, so higher-order formulations of those schemes are not so attractive in practice. Optimal schemes of second-order linear two-, three-, and four-step methods, and their equivalent single-step formulations, were recently proposed in [43].…”