Ejemplo n.º 1
0
    def construct_X_qnmat(self, addlist):

        pbond = self.model.pbond_list
        xqnl = np.array(self.cv_mpo.qn[addlist[0]])
        xqnr = np.array(self.cv_mpo.qn[addlist[-1] + 1])
        xqnmat = xqnl.copy()
        xqnsigmalist = []
        for idx in addlist:
            sigmaqn = self.model.basis[idx].sigmaqn
            xqnsigma = np.array(list(product(sigmaqn, repeat=2)))
            xqnsigma = xqnsigma.reshape(pbond[idx], pbond[idx], 2)

            xqnmat = self.qnmat_add(xqnmat, xqnsigma)
            xqnsigmalist.append(xqnsigma)

        xqnmat = self.qnmat_add(xqnmat, xqnr)
        matshape = list(xqnmat.shape)
        if self.method == "1site":
            if xqnmat.ndim == 4:
                if not self.cv_mpo.to_right:
                    xqnmat = np.moveaxis(xqnmat.reshape(matshape + [1]), -1,
                                         -2)
                else:
                    xqnmat = xqnmat.reshape([1] + matshape)
            if not self.cv_mpo.to_right:
                xqnbigl = xqnl.copy()
                xqnbigr = self.qnmat_add(xqnsigmalist[0], xqnr)
                if xqnbigr.ndim == 3:
                    rshape = list(xqnbigr.shape)
                    xqnbigr = np.moveaxis(xqnbigr.reshape(rshape + [1]), -1,
                                          -2)
            else:
                xqnbigl = self.qnmat_add(xqnl, xqnsigmalist[0])
                xqnbigr = xqnr.copy()
                if xqnbigl.ndim == 3:
                    lshape = list(xqnbigl.shape)
                    xqnbigl = xqnbigl.reshape([1] + lshape)
        else:
            if xqnmat.ndim == 6:
                if addlist[0] != 0:
                    xqnmat = np.moveaxis(xqnmat.resahpe(matshape + [1]), -1,
                                         -2)
                else:
                    xqnmat = xqnmat.reshape([1] + matshape)
            xqnbigl = self.qnmat_add(xqnl, xqnsigmalist[0])
            if xqnbigl.ndim == 3:
                lshape = list(xqnbigl.shape)
                xqnbigl = xqnbigl.reshape([1] + lshape)
            xqnbigr = self.qnmat_add(xqnsigmalist[-1], xqnr)
            if xqnbigr.ndim == 3:
                rshape = list(xqnbigr.shape)
                xqnbigr = np.moveaxis(xqnbigr.reshape(rshape + [1]), -1, -2)
        xshape = list(xqnmat.shape)
        del xshape[-1]
        if len(xshape) == 3:
            if not self.cv_mpo.to_right:
                xshape = xshape + [1]
            else:
                xshape = [1] + xshape
        return xqnmat, xqnbigl, xqnbigr, xshape
Ejemplo n.º 2
0
    def swap(self, mat, qnbigl, qnbigr, direction):
        def inter_change(ori_mat):
            matshape = ori_mat.shape
            len_mat = int(np.prod(np.array(matshape[:-1])))
            ori_mat = ori_mat.reshape(len_mat, 2)
            change_mat = copy.deepcopy(ori_mat)
            change_mat[:, 0], change_mat[:, 1] = ori_mat[:, 1], ori_mat[:, 0]
            return change_mat.reshape(matshape)

        dag_qnmat = inter_change(mat)
        if self.method == "1site":
            dag_qnmat = np.moveaxis(dag_qnmat, [1, 2], [2, 1])
            dag_qnbigl = inter_change(qnbigl)
            dag_qnbigr = inter_change(qnbigr)
            if direction == "left":
                dag_qnbigr = np.moveaxis(dag_qnbigr, [0, 1], [1, 0])
            else:
                dag_qnbigl = np.moveaxis(dag_qnbigl, [1, 2], [2, 1])
        else:
            raise NotImplementedError
            # we don't recommend 2-site CV-DMRG, which is a huge cost

        return dag_qnmat, dag_qnbigl, dag_qnbigr
Ejemplo n.º 3
0
    def x_svd(self, xstruct, xqnbigl, xqnbigr, nexciton, direction, percent=0):
        Gamma = xstruct.reshape(
            np.prod(xqnbigl.shape) // 2,
            np.prod(xqnbigr.shape) // 2)

        localXqnl = xqnbigl.ravel()
        localXqnr = xqnbigr.ravel()
        list_locall = []
        list_localr = []
        for i in range(0, len(localXqnl), 2):
            list_locall.append([localXqnl[i], localXqnl[i + 1]])
        for i in range(0, len(localXqnr), 2):
            list_localr.append([localXqnr[i], localXqnr[i + 1]])
        localXqnl = copy.deepcopy(list_locall)
        localXqnr = copy.deepcopy(list_localr)
        xuset = []
        xuset0 = []
        xvset = []
        xvset0 = []
        xsset = []
        xsuset0 = []
        xsvset0 = []
        xqnlset = []
        xqnlset0 = []
        xqnrset = []
        xqnrset0 = []
        if self.spectratype == "abs":
            combine = [[[y, 0], [nexciton - y, 0]]
                       for y in range(nexciton + 1)]
        elif self.spectratype == "emi":
            combine = [[[0, y], [0, nexciton - y]]
                       for y in range(nexciton + 1)]
        for nl, nr in combine:
            lset = np.where(self.condition(np.array(localXqnl), [nl]))[0]
            rset = np.where(self.condition(np.array(localXqnr), [nr]))[0]
            if len(lset) != 0 and len(rset) != 0:
                Gamma_block = Gamma.ravel().take(
                    (lset * Gamma.shape[1]).reshape(-1, 1) + rset)
                try:
                    U, S, Vt = \
                        scipy.linalg.svd(Gamma_block, full_matrices=True,
                                         lapack_driver='gesdd')
                except:
                    U, S, Vt = \
                        scipy.linalg.svd(Gamma_block, full_matrices=True,
                                         lapack_driver='gesvd')

                dim = S.shape[0]

                xsset.append(S)
                # U part quantum number
                xuset.append(
                    svd_qn.blockrecover(lset, U[:, :dim], Gamma.shape[0]))
                xqnlset += [nl] * dim
                xuset0.append(
                    svd_qn.blockrecover(lset, U[:, dim:], Gamma.shape[0]))
                xqnlset0 += [nl] * (U.shape[0] - dim)
                xsuset0.append(np.zeros(U.shape[0] - dim))
                # V part quantum number
                VT = Vt.T
                xvset.append(
                    svd_qn.blockrecover(rset, VT[:, :dim], Gamma.shape[1]))
                xqnrset += [nr] * dim
                xvset0.append(
                    svd_qn.blockrecover(rset, VT[:, dim:], Gamma.shape[1]))
                xqnrset0 += [nr] * (VT.shape[0] - dim)
                xsvset0.append(np.zeros(VT.shape[0] - dim))
        xuset = np.concatenate(xuset + xuset0, axis=1)
        xvset = np.concatenate(xvset + xvset0, axis=1)
        xsuset = np.concatenate(xsset + xsuset0)
        xsvset = np.concatenate(xsset + xsvset0)
        xqnlset = xqnlset + xqnlset0
        xqnrset = xqnrset + xqnrset0
        bigl_shape = list(xqnbigl.shape)
        del bigl_shape[-1]
        bigr_shape = list(xqnbigr.shape)
        del bigr_shape[-1]
        if direction == "left":
            x, xdim, xqn, compx = update_cv(xvset,
                                            xsvset,
                                            xqnrset,
                                            xuset,
                                            nexciton,
                                            self.m_max,
                                            self.spectratype,
                                            percent=percent)
            if (self.method == "1site") and (len(bigr_shape + [xdim]) == 3):
                return np.moveaxis(
                    x.reshape(bigr_shape + [1] + [xdim]), -1, 0),\
                    xdim, xqn, compx.reshape(bigl_shape + [xdim])
            else:
                return np.moveaxis(x.reshape(bigr_shape + [xdim]), -1, 0),\
                    xdim, xqn, compx.reshape(bigl_shape + [xdim])
        elif direction == "right":
            x, xdim, xqn, compx = update_cv(xuset,
                                            xsuset,
                                            xqnlset,
                                            xvset,
                                            nexciton,
                                            self.m_max,
                                            self.spectratype,
                                            percent=percent)
            if (self.method == "1site") and (len(bigl_shape + [xdim]) == 3):
                return x.reshape([1] + bigl_shape + [xdim]), xdim, xqn, \
                    np.moveaxis(compx.reshape(bigr_shape + [xdim]), -1, 0)
            else:
                return x.reshape(bigl_shape + [xdim]), xdim, xqn, \
                    np.moveaxis(compx.reshape(bigr_shape + [xdim]), -1, 0)
Ejemplo n.º 4
0
    def construct_X_qnmat(self, addlist, direction):

        pbond = self.mol_list.pbond_list
        xqnl = np.array(self.cv_mpo.qn[addlist[0]])
        xqnr = np.array(self.cv_mpo.qn[addlist[-1] + 1])
        xqnmat = xqnl.copy()
        xqnsigmalist = []
        for idx in addlist:
            if self.mol_list.ephtable.is_electron(idx):
                xqnsigma = np.array([[[0, 0], [0, 1]], [[1, 0], [1, 1]]])
            else:
                xqnsigma = []
                for i in range((pbond[idx])**2):
                    xqnsigma.append([0, 0])
                xqnsigma = np.array(xqnsigma)
                xqnsigma = xqnsigma.reshape(pbond[idx], pbond[idx], 2)

            xqnmat = self.qnmat_add(xqnmat, xqnsigma)
            xqnsigmalist.append(xqnsigma)

        xqnmat = self.qnmat_add(xqnmat, xqnr)
        matshape = list(xqnmat.shape)
        if self.method == "1site":
            if xqnmat.ndim == 4:
                if direction == "left":
                    xqnmat = np.moveaxis(xqnmat.reshape(matshape + [1]), -1,
                                         -2)
                else:
                    xqnmat = xqnmat.reshape([1] + matshape)
            if direction == "left":
                xqnbigl = xqnl.copy()
                xqnbigr = self.qnmat_add(xqnsigmalist[0], xqnr)
                if xqnbigr.ndim == 3:
                    rshape = list(xqnbigr.shape)
                    xqnbigr = np.moveaxis(xqnbigr.reshape(rshape + [1]), -1,
                                          -2)
            else:
                xqnbigl = self.qnmat_add(xqnl, xqnsigmalist[0])
                xqnbigr = xqnr.copy()
                if xqnbigl.ndim == 3:
                    lshape = list(xqnbigl.shape)
                    xqnbigl = xqnbigl.reshape([1] + lshape)
        else:
            if xqnmat.ndim == 6:
                if addlist[0] != 0:
                    xqnmat = np.moveaxis(xqnmat.resahpe(matshape + [1]), -1,
                                         -2)
                else:
                    xqnmat = xqnmat.reshape([1] + matshape)
            xqnbigl = self.qnmat_add(xqnl, xqnsigmalist[0])
            if xqnbigl.ndim == 3:
                lshape = list(xqnbigl.shape)
                xqnbigl = xqnbigl.reshape([1] + lshape)
            xqnbigr = self.qnmat_add(xqnsigmalist[-1], xqnr)
            if xqnbigr.ndim == 3:
                rshape = list(xqnbigr.shape)
                xqnbigr = np.moveaxis(xqnbigr.reshape(rshape + [1]), -1, -2)
        xshape = list(xqnmat.shape)
        del xshape[-1]
        if len(xshape) == 3:
            if direction == "left":
                xshape = xshape + [1]
            elif direction == "right":
                xshape = [1] + xshape
        return xqnmat, xqnbigl, xqnbigr, xshape
Ejemplo n.º 5
0
    def optimize_cv(self, lr_group, direction, isite, num, percent=0):
        if self.spectratype == "abs":
            # quantum number restriction, |1><0|
            up_exciton, down_exciton = 1, 0
        elif self.spectratype == "emi":
            # quantum number restriction, |0><1|
            up_exciton, down_exciton = 0, 1
        nexciton = 1
        first_LR, second_LR, third_LR, forth_LR = lr_group

        if self.method == "1site":
            add_list = [isite - 1]
            first_L = asxp(first_LR[isite - 1])
            first_R = asxp(first_LR[isite])
            second_L = asxp(second_LR[isite - 1])
            second_R = asxp(second_LR[isite])
            third_L = asxp(third_LR[isite - 1])
            third_R = asxp(third_LR[isite])
            forth_L = asxp(forth_LR[isite - 1])
            forth_R = asxp(forth_LR[isite])
        else:
            add_list = [isite - 2, isite - 1]
            first_L = asxp(first_LR[isite - 2])
            first_R = asxp(first_LR[isite])
            second_L = asxp(second_LR[isite - 2])
            second_R = asxp(second_LR[isite])
            third_L = asxp(third_LR[isite - 2])
            third_R = asxp(third_LR[isite])
            forth_L = asxp(forth_LR[isite - 2])
            forth_R = asxp(forth_LR[isite])

        xqnmat, xqnbigl, xqnbigr, xshape = \
            self.construct_X_qnmat(add_list, direction)
        dag_qnmat, dag_qnbigl, dag_qnbigr = self.swap(xqnmat, xqnbigl, xqnbigr,
                                                      direction)

        nonzeros = np.sum(self.condition(dag_qnmat,
                                         [down_exciton, up_exciton]))

        if self.method == "1site":
            guess = moveaxis(self.cv_mpo[isite - 1], (1, 2), (2, 1))
        else:
            guess = tensordot(moveaxis(self.cv_mpo[isite - 2], (1, 2), (2, 1)),
                              moveaxis(self.cv_mpo[isite - 1]),
                              axes=(-1, 0))
        guess = guess[self.condition(dag_qnmat,
                                     [down_exciton, up_exciton])].reshape(
                                         nonzeros, 1)

        if self.method == "1site":
            # define dot path
            path_1 = [([0, 1], "abc, adef -> bcdef"),
                      ([2, 0], "bcdef, begh -> cdfgh"),
                      ([1, 0], "cdfgh, fhi -> cdgi")]
            path_2 = [([0, 1], "abcd, aefg -> bcdefg"),
                      ([3, 0], "bcdefg, bfhi -> cdeghi"),
                      ([2, 0], "cdeghi, djek -> cghijk"),
                      ([1, 0], "cghijk, gilk -> chjl")]
            path_4 = [([0, 1], "ab, acde -> bcde"), ([1,
                                                      0], "bcde, ef -> bcdf")]

            vecb = multi_tensor_contract(
                path_4, forth_L,
                moveaxis(self.a_ket_mpo[isite - 1], (1, 2), (2, 1)), forth_R)
            vecb = -self.eta * vecb

        a_oper_isite = asxp(self.a_oper[isite - 1])
        b_oper_isite = asxp(self.b_oper[isite - 1])
        h_mpo_isite = asxp(self.h_mpo[isite - 1])
        # construct preconditioner
        Idt = xp.identity(h_mpo_isite.shape[1])
        M1_1 = xp.einsum('aea->ae', first_L)
        M1_2 = xp.einsum('eccf->ecf', a_oper_isite)
        M1_3 = xp.einsum('dfd->df', first_R)
        M1_4 = xp.einsum('bb->b', Idt)
        path_m1 = [([0, 1], "ae,b->aeb"), ([2, 0], "aeb,ecf->abcf"),
                   ([1, 0], "abcf, df->abcd")]
        pre_M1 = multi_tensor_contract(path_m1, M1_1, M1_4, M1_2, M1_3)
        pre_M1 = pre_M1[self.condition(dag_qnmat, [down_exciton, up_exciton])]

        M2_1 = xp.einsum('aeag->aeg', second_L)
        M2_2 = xp.einsum('eccf->ecf', b_oper_isite)
        M2_3 = xp.einsum('gbbh->gbh', h_mpo_isite)
        M2_4 = xp.einsum('dfdh->dfh', second_R)
        path_m2 = [([0, 1], "aeg,gbh->aebh"), ([2, 0], "aebh,ecf->abchf"),
                   ([1, 0], "abhcf,dfh->abcd")]
        pre_M2 = multi_tensor_contract(path_m2, M2_1, M2_3, M2_2, M2_4)
        pre_M2 = pre_M2[self.condition(dag_qnmat, [down_exciton, up_exciton])]

        M4_1 = xp.einsum('faah->fah', third_L)
        M4_4 = xp.einsum('gddi->gdi', third_R)
        M4_5 = xp.einsum('cc->c', Idt)
        M4_path = [([0, 1], "fah,febg->ahebg"), ([2, 0], "ahebg,hjei->abgji"),
                   ([1, 0], "abgji,gdi->abjd")]
        pre_M4 = multi_tensor_contract(M4_path, M4_1, h_mpo_isite, h_mpo_isite,
                                       M4_4)
        pre_M4 = xp.einsum('abbd->abd', pre_M4)
        pre_M4 = xp.tensordot(pre_M4, M4_5, axes=0)
        pre_M4 = xp.moveaxis(pre_M4, [2, 3], [3, 2])[self.condition(
            dag_qnmat, [down_exciton, up_exciton])]

        pre_M = (pre_M1 + 2 * pre_M2 + pre_M4)

        indices = np.array(range(nonzeros))
        indptr = np.array(range(nonzeros + 1))
        pre_M = scipy.sparse.csc_matrix((asnumpy(pre_M), indices, indptr),
                                        shape=(nonzeros, nonzeros))

        M_x = lambda x: scipy.sparse.linalg.spsolve(pre_M, x)
        M = scipy.sparse.linalg.LinearOperator((nonzeros, nonzeros), M_x)

        count = 0

        def hop(x):
            nonlocal count
            count += 1
            dag_struct = asxp(self.dag2mat(xshape, x, dag_qnmat, direction))
            if self.method == "1site":

                M1 = multi_tensor_contract(path_1, first_L, dag_struct,
                                           a_oper_isite, first_R)
                M2 = multi_tensor_contract(path_2, second_L, dag_struct,
                                           b_oper_isite, h_mpo_isite, second_R)
                M2 = xp.moveaxis(M2, (1, 2), (2, 1))
                M3 = multi_tensor_contract(path_2, third_L, h_mpo_isite,
                                           dag_struct, h_mpo_isite, third_R)
                M3 = xp.moveaxis(M3, (1, 2), (2, 1))
                cout = M1 + 2 * M2 + M3
            cout = cout[self.condition(dag_qnmat,
                                       [down_exciton, up_exciton])].reshape(
                                           nonzeros, 1)
            return asnumpy(cout)

        # Matrix A and Vector b
        vecb = asnumpy(vecb)[self.condition(
            dag_qnmat, [down_exciton, up_exciton])].reshape(nonzeros, 1)
        mata = scipy.sparse.linalg.LinearOperator((nonzeros, nonzeros),
                                                  matvec=hop)

        # conjugate gradient method
        # x, info = scipy.sparse.linalg.cg(MatA, VecB, atol=0)
        if num == 1:
            x, info = scipy.sparse.linalg.cg(mata,
                                             vecb,
                                             tol=1.e-5,
                                             maxiter=500,
                                             M=M,
                                             atol=0)
        else:
            x, info = scipy.sparse.linalg.cg(mata,
                                             vecb,
                                             tol=1.e-5,
                                             x0=guess,
                                             maxiter=500,
                                             M=M,
                                             atol=0)
        # logger.info(f"linear eq dim: {nonzeros}")
        # logger.info(f'times for hop:{count}')
        self.hop_time.append(count)
        if info != 0:
            logger.warning(
                f"cg not converged, vecb.norm:{np.linalg.norm(vecb)}")
        l_value = np.inner(
            hop(x).reshape(1, nonzeros), x.reshape(1, nonzeros)) - \
            2 * np.inner(vecb.reshape(1, nonzeros), x.reshape(1, nonzeros))

        x = self.dag2mat(xshape, x, dag_qnmat, direction)
        if self.method == "1site":
            x = np.moveaxis(x, [1, 2], [2, 1])
        x, xdim, xqn, compx = self.x_svd(x,
                                         xqnbigl,
                                         xqnbigr,
                                         nexciton,
                                         direction,
                                         percent=percent)

        if self.method == "1site":
            self.cv_mpo[isite - 1] = x
            if direction == "left":
                if isite != 1:
                    self.cv_mpo[isite - 2] = \
                        tensordot(self.cv_mpo[isite - 2], compx, axes=(-1, 0))
                    self.cv_mpo.qn[isite - 1] = xqn
                else:
                    self.cv_mpo[isite - 1] = \
                        tensordot(compx, self.cv_mpo[isite - 1], axes=(-1, 0))
            elif direction == "right":
                if isite != len(self.cv_mpo):
                    self.cv_mpo[isite] = \
                        tensordot(compx, self.cv_mpo[isite], axes=(-1, 0))
                    self.cv_mpo.qn[isite] = xqn
                else:
                    self.cv_mpo[isite - 1] = \
                        tensordot(self.cv_mpo[isite - 1], compx, axes=(-1, 0))

        else:
            if direction == "left":
                self.cv_mpo[isite - 2] = compx
                self.cv_mpo[isite - 1] = x
            else:
                self.cv_mpo[isite - 2] = x
                self.cv_mpo[isite - 1] = compx
            self.cv_mpo.qn[isite - 1] = xqn

        return l_value[0][0]
Ejemplo n.º 6
0
def moveaxis(a: Matrix, source, destination):
    return Matrix(np.moveaxis(a.array, source, destination))
Ejemplo n.º 7
0
    def optimize_cv(self, lr_group, isite, percent=0):
        if self.spectratype == "abs":
            # quantum number restriction, |1><0|
            up_exciton, down_exciton = 1, 0
        elif self.spectratype == "emi":
            # quantum number restriction, |0><1|
            up_exciton, down_exciton = 0, 1
        nexciton = 1
        first_LR, second_LR, third_LR, forth_LR = lr_group

        if self.method == "1site":
            add_list = [isite - 1]
            first_L = asxp(first_LR[isite - 1])
            first_R = asxp(first_LR[isite])
            second_L = asxp(second_LR[isite - 1])
            second_R = asxp(second_LR[isite])
            third_L = asxp(third_LR[isite - 1])
            third_R = asxp(third_LR[isite])
            forth_L = asxp(forth_LR[isite - 1])
            forth_R = asxp(forth_LR[isite])
        else:
            add_list = [isite - 2, isite - 1]
            first_L = asxp(first_LR[isite - 2])
            first_R = asxp(first_LR[isite])
            second_L = asxp(second_LR[isite - 2])
            second_R = asxp(second_LR[isite])
            third_L = asxp(third_LR[isite - 2])
            third_R = asxp(third_LR[isite])
            forth_L = asxp(forth_LR[isite - 2])
            forth_R = asxp(forth_LR[isite])

        xqnmat, xqnbigl, xqnbigr, xshape = \
            self.construct_X_qnmat(add_list)
        dag_qnmat, dag_qnbigl, dag_qnbigr = self.swap(xqnmat, xqnbigl, xqnbigr)
        nonzeros = int(
            np.sum(self.condition(dag_qnmat, [down_exciton, up_exciton])))

        if self.method == "1site":
            guess = moveaxis(self.cv_mpo[isite - 1], (1, 2), (2, 1))
        else:
            guess = tensordot(moveaxis(self.cv_mpo[isite - 2], (1, 2), (2, 1)),
                              moveaxis(self.cv_mpo[isite - 1]),
                              axes=(-1, 0))
        guess = guess[self.condition(dag_qnmat, [down_exciton, up_exciton])]

        if self.method == "1site":
            # define dot path
            path_1 = [([0, 1], "abcd, aefg -> bcdefg"),
                      ([3, 0], "bcdefg, bfhi -> cdeghi"),
                      ([2, 0], "cdeghi, chjk -> degijk"),
                      ([1, 0], "degijk, gikl -> dejl")]
            path_2 = [([0, 1], "abcd, aefg -> bcdefg"),
                      ([3, 0], "bcdefg, bfhi -> cdeghi"),
                      ([2, 0], "cdeghi, djek -> cghijk"),
                      ([1, 0], "cghijk, gilk -> chjl")]
            path_3 = [([0, 1], "ab, acde -> bcde"), ([1,
                                                      0], "bcde, ef -> bcdf")]

            vecb = multi_tensor_contract(
                path_3, forth_L, moveaxis(self.b_mpo[isite - 1], (1, 2),
                                          (2, 1)),
                forth_R)[self.condition(dag_qnmat, [down_exciton, up_exciton])]

        a_oper_isite = asxp(self.a_oper[isite - 1])
        h_mpo_isite = asxp(self.h_mpo[isite - 1])
        # construct preconditioner
        Idt = xp.identity(h_mpo_isite.shape[1])
        M1_1 = xp.einsum('abca->abc', first_L)
        path_m1 = [([0, 1], "abc, bdef->acdef"), ([1,
                                                   0], "acdef, cegh->adfgh")]
        M1_2 = multi_tensor_contract(path_m1, M1_1, a_oper_isite, a_oper_isite)
        M1_2 = xp.einsum("abcbd->abcd", M1_2)
        M1_3 = xp.einsum('ecde->ecd', first_R)
        M1_4 = xp.einsum('ff->f', Idt)
        path_m1 = [([0, 1], "abcd,ecd->abe"), ([1, 0], "abe,f->abef")]
        pre_M1 = multi_tensor_contract(path_m1, M1_2, M1_3, M1_4)
        pre_M1 = xp.moveaxis(pre_M1, [-2, -1], [-1, -2])[self.condition(
            dag_qnmat, [down_exciton, up_exciton])]

        M2_1 = xp.einsum('aeag->aeg', second_L)
        M2_2 = xp.einsum('eccf->ecf', a_oper_isite)
        M2_3 = xp.einsum('gbbh->gbh', h_mpo_isite)
        M2_4 = xp.einsum('dfdh->dfh', second_R)
        path_m2 = [([0, 1], "aeg,gbh->aebh"), ([2, 0], "aebh,ecf->abchf"),
                   ([1, 0], "abhcf,dfh->abcd")]
        pre_M2 = multi_tensor_contract(path_m2, M2_1, M2_3, M2_2, M2_4)
        pre_M2 = pre_M2[self.condition(dag_qnmat, [down_exciton, up_exciton])]

        M4_1 = xp.einsum('faah->fah', third_L)
        M4_4 = xp.einsum('gddi->gdi', third_R)
        M4_5 = xp.einsum('cc->c', Idt)
        M4_path = [([0, 1], "fah,febg->ahebg"), ([2, 0], "ahebg,hjei->abgji"),
                   ([1, 0], "abgji,gdi->abjd")]
        pre_M4 = multi_tensor_contract(M4_path, M4_1, h_mpo_isite, h_mpo_isite,
                                       M4_4)
        pre_M4 = xp.einsum('abbd->abd', pre_M4)
        pre_M4 = xp.tensordot(pre_M4, M4_5, axes=0)
        pre_M4 = xp.moveaxis(pre_M4, [2, 3], [3, 2])[self.condition(
            dag_qnmat, [down_exciton, up_exciton])]

        M_x = lambda x: asnumpy(
            asxp(x) /
            (pre_M1 + 2 * pre_M2 + pre_M4 + xp.ones(nonzeros) * self.eta**2))
        pre_M = scipy.sparse.linalg.LinearOperator((nonzeros, nonzeros), M_x)

        count = 0

        def hop(x):
            nonlocal count
            count += 1
            dag_struct = asxp(self.dag2mat(xshape, x, dag_qnmat))
            if self.method == "1site":

                M1 = multi_tensor_contract(path_1, first_L, dag_struct,
                                           a_oper_isite, a_oper_isite, first_R)
                M2 = multi_tensor_contract(path_2, second_L, dag_struct,
                                           a_oper_isite, h_mpo_isite, second_R)
                M2 = xp.moveaxis(M2, (1, 2), (2, 1))
                M3 = multi_tensor_contract(path_2, third_L, h_mpo_isite,
                                           dag_struct, h_mpo_isite, third_R)
                M3 = xp.moveaxis(M3, (1, 2), (2, 1))
                cout = M1 + 2 * M2 + M3 + dag_struct * self.eta**2
            cout = cout[self.condition(dag_qnmat, [down_exciton, up_exciton])]
            return asnumpy(cout)

        # Matrix A
        mat_a = scipy.sparse.linalg.LinearOperator((nonzeros, nonzeros),
                                                   matvec=hop)

        x, info = scipy.sparse.linalg.cg(mat_a,
                                         asnumpy(vecb),
                                         tol=1.e-5,
                                         x0=asnumpy(guess),
                                         maxiter=500,
                                         M=pre_M,
                                         atol=0)
        # logger.info(f"linear eq dim: {nonzeros}")
        # logger.info(f'times for hop:{count}')
        self.hop_time.append(count)
        if info != 0:
            logger.warning(
                f"cg not converged, vecb.norm:{xp.linalg.norm(vecb)}")
        l_value = xp.dot(asxp(hop(x)), asxp(x)) - 2 * xp.dot(vecb, asxp(x))

        x = self.dag2mat(xshape, x, dag_qnmat)
        if self.method == "1site":
            x = np.moveaxis(x, [1, 2], [2, 1])
        x, xdim, xqn, compx = self.x_svd(x,
                                         xqnbigl,
                                         xqnbigr,
                                         nexciton,
                                         percent=percent)

        if self.method == "1site":
            self.cv_mpo[isite - 1] = x
            if not self.cv_mpo.to_right:
                if isite != 1:
                    self.cv_mpo[isite - 2] = \
                        tensordot(self.cv_mpo[isite - 2], compx, axes=(-1, 0))
                    self.cv_mpo.qn[isite - 1] = xqn
                    self.cv_mpo.qnidx = isite - 2
                else:
                    self.cv_mpo[isite - 1] = \
                        tensordot(compx, self.cv_mpo[isite - 1], axes=(-1, 0))
                    self.cv_mpo.qnidx = 0
            else:
                if isite != len(self.cv_mpo):
                    self.cv_mpo[isite] = \
                        tensordot(compx, self.cv_mpo[isite], axes=(-1, 0))
                    self.cv_mpo.qn[isite] = xqn
                    self.cv_mpo.qnidx = isite
                else:
                    self.cv_mpo[isite - 1] = \
                        tensordot(self.cv_mpo[isite - 1], compx, axes=(-1, 0))
                    self.cv_mpo.qnidx = self.cv_mpo.site_num - 1

        else:
            if not self.cv_mpo.to_right:
                self.cv_mpo[isite - 2] = compx
                self.cv_mpo[isite - 1] = x
                self.cv_mpo.qnidx = isite - 2
            else:
                self.cv_mpo[isite - 2] = x
                self.cv_mpo[isite - 1] = compx
                self.cv_mpo.qnidx = isite - 1
            self.cv_mpo.qn[isite - 1] = xqn

        return float(l_value)