I am testing an example of the 'cut' function in ASE cut. In this example, the surface Al(111) is created using vectors (1, -1, 0) and (0, 1, -1) included in the "cut" function. But I am not clear how to define those vectors (1, -1, 0) and (0, 1, -1). Can you help me to explain? If I have to crea...