“…The CMX is quite appealing because it provides approximate values for the ground-state energy of a quantum system directly in terms of a finite number of connected mo-ments. This may be the reason why the CMX and its variants [4,6,7] were applied to several simple physical problems [5,6,[8][9][10][11][12][13][14][15] in spite of its limitations [4,6,7,12,13,[16][17][18]. In order to overcome some of the drawbacks of the CMX several authors have proposed alternative strategies like the generalized moment expansion (GMX) [19][20][21].…”