linalg.py 文件源码

def _eig_local_op_mps(lv, ltens, rv):
    """Local operator contribution from an MPS"""
    # MPS 1 / ltens: Interpreted as |psiXpsi| part of the operator
    # MPS 2: The current eigvectector candidate
    op = lv.T
    # op axes: 0 mps2 bond, 1: mps1 bond
    s = op.shape
    op = op.reshape((s[0], 1, s[1]))
    # op axes: 0 mps2 bond, 1: physical legs, 2: mps1 bond
    for lt in ltens:
        # op axes: 0: mps2 bond, 1: physical legs, 2: mps1 bond
        op = np.tensordot(op, lt.conj(), axes=(2, 0))
        # op axes: 0: mps2 bond, 1, 2: physical legs, 3: mps1 bond
        s = op.shape
        op = op.reshape((s[0], -1, s[3]))
        # op axes: 0: mps2 bond, 1: physical legs, 2: mps1 bond
    op = np.tensordot(op, rv, axes=(2, 0))
    # op axes: 0: mps2 bond, 1: physical legs, 2: mps2 bond
    op = np.outer(op.conj(), op)
    # op axes:
    # 0: (0a: left cc mps2 bond, 0b: physical row leg, 0c: right cc mps2 bond),
    # 1: (1a: left mps2 bond, 1b: physical column leg, 1c: right mps2 bond)
    return op