Exemple #1
0
    def get_rpa(self):
        """Calculate RPA and Hartree-fock part of the A+-B matrices."""

        # shorthands
        kss = self.fullkss
        finegrid = self.finegrid
        yukawa = hasattr(self.xc, 'rsf') and (self.xc.rsf == 'Yukawa')

        # calculate omega matrix
        nij = len(kss)
        print('RPAhyb', nij, 'transitions', file=self.txt)

        AmB = np.zeros((nij, nij))
        ApB = self.ApB

        # storage place for Coulomb integrals
        integrals = {}
        if yukawa:
            rsf_integrals = {}
        # setup things for IVOs
        if self.xc.excitation is not None or self.xc.excited != 0:
            sin_tri_weight = 1
            if self.xc.excitation is not None:
                ex_type = self.xc.excitation.lower()
                if ex_type == 'singlet':
                    sin_tri_weight = 2
                elif ex_type == 'triplet':
                    sin_tri_weight = 0
            h**o = int(self.paw.get_number_of_electrons() // 2)
            ivo_l = h**o - self.xc.excited - 1
        else:
            ivo_l = None

        for ij in range(nij):
            print('RPAhyb kss[' + '%d' % ij + ']=', kss[ij], file=self.txt)

            timer = Timer()
            timer.start('init')
            timer2 = Timer()

            # smooth density including compensation charges
            timer2.start('with_compensation_charges 0')
            rhot_p = kss[ij].with_compensation_charges(finegrid != 0)
            timer2.stop()

            # integrate with 1/|r_1-r_2|
            timer2.start('poisson')
            phit_p = np.zeros(rhot_p.shape, rhot_p.dtype)
            self.poisson.solve(phit_p, rhot_p, charge=None)
            timer2.stop()

            timer.stop()
            t0 = timer.get_time('init')
            timer.start(ij)

            if finegrid == 1:
                rhot = kss[ij].with_compensation_charges()
                phit = self.gd.zeros()
                self.restrict(phit_p, phit)
            else:
                phit = phit_p
                rhot = rhot_p

            for kq in range(ij, nij):
                if kq != ij:
                    # smooth density including compensation charges
                    timer2.start('kq with_compensation_charges')
                    rhot = kss[kq].with_compensation_charges(finegrid == 2)
                    timer2.stop()
                pre = self.weight_Kijkq(ij, kq)

                timer2.start('integrate')
                I = self.Coulomb_integral_kss(kss[ij], kss[kq], phit, rhot)
                if kss[ij].spin == kss[kq].spin:
                    name = self.Coulomb_integral_name(kss[ij].i, kss[ij].j,
                                                      kss[kq].i, kss[kq].j,
                                                      kss[ij].spin)
                    integrals[name] = I
                ApB[ij, kq] = pre * I
                timer2.stop()

                if ij == kq:
                    epsij = kss[ij].get_energy() / kss[ij].get_weight()
                    AmB[ij, kq] += epsij
                    ApB[ij, kq] += epsij

            timer.stop()
            # timer2.write()
            if ij < (nij - 1):
                print('RPAhyb estimated time left',
                      self.time_left(timer, t0, ij, nij),
                      file=self.txt)

        # add HF parts and apply symmetry
        if hasattr(self.xc, 'hybrid'):
            weight = self.xc.hybrid
        else:
            weight = 0.0
        for ij in range(nij):
            print('HF kss[' + '%d' % ij + ']', file=self.txt)
            timer = Timer()
            timer.start('init')
            timer.stop()
            t0 = timer.get_time('init')
            timer.start(ij)

            i = kss[ij].i
            j = kss[ij].j
            s = kss[ij].spin
            for kq in range(ij, nij):
                if kss[ij].pspin == kss[kq].pspin:
                    k = kss[kq].i
                    q = kss[kq].j
                    ikjq = self.Coulomb_integral_ijkq(i, k, j, q, s, integrals)
                    iqkj = self.Coulomb_integral_ijkq(i, q, k, j, s, integrals)
                    if yukawa:  # Yukawa integrals might be caches
                        ikjq -= self.Coulomb_integral_ijkq(
                            i, k, j, q, s, rsf_integrals, yukawa)
                        iqkj -= self.Coulomb_integral_ijkq(
                            i, q, k, j, s, rsf_integrals, yukawa)
                    ApB[ij, kq] -= weight * (ikjq + iqkj)
                    AmB[ij, kq] -= weight * (ikjq - iqkj)

                ApB[kq, ij] = ApB[ij, kq]
                AmB[kq, ij] = AmB[ij, kq]

            timer.stop()
            if ij < (nij - 1):
                print('HF estimated time left',
                      self.time_left(timer, t0, ij, nij),
                      file=self.txt)

        if ivo_l is not None:
            # IVO RPA after Berman, Kaldor, Chem. Phys. 43 (3) 1979
            # doi: 10.1016/0301-0104(79)85205-2
            l = ivo_l
            for ij in range(nij):
                i = kss[ij].i
                j = kss[ij].j
                s = kss[ij].spin
                for kq in range(ij, nij):
                    if kss[kq].i == i and kss[ij].pspin == kss[kq].pspin:
                        k = kss[kq].i
                        q = kss[kq].j
                        jqll = self.Coulomb_integral_ijkq(
                            j, q, l, l, s, integrals)
                        jllq = self.Coulomb_integral_ijkq(
                            j, l, l, q, s, integrals)
                        if yukawa:
                            jqll -= self.Coulomb_integral_ijkq(
                                j, q, l, l, s, rsf_integrals, yukawa)
                            jllq -= self.Coulomb_integral_ijkq(
                                j, l, l, q, s, rsf_integrals, yukawa)
                        jllq *= sin_tri_weight
                        ApB[ij, kq] += weight * (jqll - jllq)
                        AmB[ij, kq] += weight * (jqll - jllq)
                        ApB[kq, ij] = ApB[ij, kq]
                        AmB[kq, ij] = AmB[ij, kq]
        return AmB
    def get_rpa(self):
        """calculate RPA part of the omega matrix"""

        # shorthands
        kss = self.fullkss
        finegrid = self.finegrid
        wfs = self.paw.wfs
        eh_comm = self.eh_comm

        # calculate omega matrix
        nij = len(kss)
        print('RPA', nij, 'transitions', file=self.txt)

        Om = self.Om

        for ij in range(eh_comm.rank, nij, eh_comm.size):
            print('RPA kss[' + '%d' % ij + ']=', kss[ij], file=self.txt)

            timer = Timer()
            timer.start('init')
            timer2 = Timer()

            # smooth density including compensation charges
            timer2.start('with_compensation_charges 0')
            rhot_p = kss[ij].with_compensation_charges(
                finegrid is not 0)
            timer2.stop()

            # integrate with 1/|r_1-r_2|
            timer2.start('poisson')
            phit_p = np.zeros(rhot_p.shape, rhot_p.dtype.char)
            self.poisson.solve(phit_p, rhot_p, charge=None)
            timer2.stop()

            timer.stop()
            t0 = timer.get_time('init')
            timer.start(ij)

            if finegrid == 1:
                rhot = kss[ij].with_compensation_charges()
                phit = self.gd.zeros()
# print "shapes 0=",phit.shape,rhot.shape
                self.restrict(phit_p, phit)
            else:
                phit = phit_p
                rhot = rhot_p

            for kq in range(ij, nij):
                if kq != ij:
                    # smooth density including compensation charges
                    timer2.start('kq with_compensation_charges')
                    rhot = kss[kq].with_compensation_charges(
                        finegrid is 2)
                    timer2.stop()

                pre = 2 * sqrt(kss[ij].get_energy() * kss[kq].get_energy() *
                               kss[ij].get_weight() * kss[kq].get_weight())
                I = self.Coulomb_integral_kss(kss[ij], kss[kq],
                                              rhot, phit, timer2)
                Om[ij, kq] = pre * I

                if ij == kq:
                    Om[ij, kq] += kss[ij].get_energy() ** 2
                else:
                    Om[kq, ij] = Om[ij, kq]

            timer.stop()
# timer2.write()
            if ij < (nij - 1):
                t = timer.get_time(ij)  # time for nij-ij calculations
                t = .5 * t * \
                    (nij - ij)  # estimated time for n*(n+1)/2, n=nij-(ij+1)
                print('RPA estimated time left',
                      self.timestring(t0 * (nij - ij - 1) + t), file=self.txt)
Exemple #3
0
    def get_rpa(self):
        """Calculate RPA and Hartree-fock part of the A+-B matrices."""

        # shorthands
        kss = self.fullkss
        finegrid = self.finegrid

        # calculate omega matrix
        nij = len(kss)
        print('RPAhyb', nij, 'transitions', file=self.txt)

        AmB = np.zeros((nij, nij))
        ApB = self.ApB

        # storage place for Coulomb integrals
        integrals = {}

        for ij in range(nij):
            print('RPAhyb kss[' + '%d' % ij + ']=', kss[ij], file=self.txt)

            timer = Timer()
            timer.start('init')
            timer2 = Timer()

            # smooth density including compensation charges
            timer2.start('with_compensation_charges 0')
            rhot_p = kss[ij].with_compensation_charges(finegrid is not 0)
            timer2.stop()

            # integrate with 1/|r_1-r_2|
            timer2.start('poisson')
            phit_p = np.zeros(rhot_p.shape, rhot_p.dtype)
            self.poisson.solve(phit_p, rhot_p, charge=None)
            timer2.stop()

            timer.stop()
            t0 = timer.get_time('init')
            timer.start(ij)

            if finegrid == 1:
                rhot = kss[ij].with_compensation_charges()
                phit = self.gd.zeros()
                self.restrict(phit_p, phit)
            else:
                phit = phit_p
                rhot = rhot_p

            for kq in range(ij, nij):
                if kq != ij:
                    # smooth density including compensation charges
                    timer2.start('kq with_compensation_charges')
                    rhot = kss[kq].with_compensation_charges(finegrid is 2)
                    timer2.stop()
                pre = self.weight_Kijkq(ij, kq)

                timer2.start('integrate')
                I = self.Coulomb_integral_kss(kss[ij], kss[kq], phit, rhot)
                if kss[ij].spin == kss[kq].spin:
                    name = self.Coulomb_integral_name(kss[ij].i, kss[ij].j,
                                                      kss[kq].i, kss[kq].j,
                                                      kss[ij].spin)
                    integrals[name] = I
                ApB[ij, kq] = pre * I
                timer2.stop()

                if ij == kq:
                    epsij = kss[ij].get_energy() / kss[ij].get_weight()
                    AmB[ij, kq] += epsij
                    ApB[ij, kq] += epsij

            timer.stop()
            # timer2.write()
            if ij < (nij - 1):
                print('RPAhyb estimated time left',
                      self.time_left(timer, t0, ij, nij),
                      file=self.txt)

        # add HF parts and apply symmetry
        if hasattr(self.xc, 'hybrid'):
            weight = self.xc.hybrid
        else:
            weight = 0.0
        for ij in range(nij):
            print('HF kss[' + '%d' % ij + ']', file=self.txt)
            timer = Timer()
            timer.start('init')
            timer.stop()
            t0 = timer.get_time('init')
            timer.start(ij)

            i = kss[ij].i
            j = kss[ij].j
            s = kss[ij].spin
            for kq in range(ij, nij):
                if kss[ij].pspin == kss[kq].pspin:
                    k = kss[kq].i
                    q = kss[kq].j
                    ikjq = self.Coulomb_integral_ijkq(i, k, j, q, s, integrals)
                    iqkj = self.Coulomb_integral_ijkq(i, q, k, j, s, integrals)
                    ApB[ij, kq] -= weight * (ikjq + iqkj)
                    AmB[ij, kq] -= weight * (ikjq - iqkj)

                ApB[kq, ij] = ApB[ij, kq]
                AmB[kq, ij] = AmB[ij, kq]

            timer.stop()
            if ij < (nij - 1):
                print('HF estimated time left',
                      self.time_left(timer, t0, ij, nij),
                      file=self.txt)

        return AmB
    def get_xc(self):
        """Add xc part of the coupling matrix"""

        # shorthands
        paw = self.paw
        wfs = paw.wfs
        gd = paw.density.finegd
        comm = gd.comm
        eh_comm = self.eh_comm

        fg = self.finegrid is 2
        kss = self.fullkss
        nij = len(kss)

        Om_xc = self.Om
        # initialize densities
        # nt_sg is the smooth density on the fine grid with spin index

        if kss.nvspins == 2:
            # spin polarised ground state calc.
            nt_sg = paw.density.nt_sg
        else:
            # spin unpolarised ground state calc.
            if kss.npspins == 2:
                # construct spin polarised densities
                nt_sg = np.array([.5 * paw.density.nt_sg[0],
                                  .5 * paw.density.nt_sg[0]])
            else:
                nt_sg = paw.density.nt_sg
        # check if D_sp have been changed before
        D_asp = self.paw.density.D_asp
        for a, D_sp in D_asp.items():
            if len(D_sp) != kss.npspins:
                if len(D_sp) == 1:
                    D_asp[a] = np.array([0.5 * D_sp[0], 0.5 * D_sp[0]])
                else:
                    D_asp[a] = np.array([D_sp[0] + D_sp[1]])

        # restrict the density if needed
        if fg:
            nt_s = nt_sg
        else:
            nt_s = self.gd.zeros(nt_sg.shape[0])
            for s in range(nt_sg.shape[0]):
                self.restrict(nt_sg[s], nt_s[s])
            gd = paw.density.gd

        # initialize vxc or fxc

        if self.derivativeLevel == 0:
            raise NotImplementedError
            if kss.npspins == 2:
                v_g = nt_sg[0].copy()
            else:
                v_g = nt_sg.copy()
        elif self.derivativeLevel == 1:
            pass
        elif self.derivativeLevel == 2:
            fxc_sg = np.zeros(nt_sg.shape)
            self.xc.calculate_fxc(gd, nt_sg, fxc_sg)
        else:
            raise ValueError('derivativeLevel can only be 0,1,2')

# self.paw.my_nuclei = []

        ns = self.numscale
        xc = self.xc
        print('XC', nij, 'transitions', file=self.txt)
        for ij in range(eh_comm.rank, nij, eh_comm.size):
            print('XC kss[' + '%d' % ij + ']', file=self.txt)

            timer = Timer()
            timer.start('init')
            timer2 = Timer()

            if self.derivativeLevel >= 1:
                # vxc is available
                # We use the numerical two point formula for calculating
                # the integral over fxc*n_ij. The results are
                # vvt_s        smooth integral
                # nucleus.I_sp atom based correction matrices (pack2)
                #              stored on each nucleus
                timer2.start('init v grids')
                vp_s = np.zeros(nt_s.shape, nt_s.dtype.char)
                vm_s = np.zeros(nt_s.shape, nt_s.dtype.char)
                if kss.npspins == 2:  # spin polarised
                    nv_s = nt_s.copy()
                    nv_s[kss[ij].pspin] += ns * kss[ij].get(fg)
                    xc.calculate(gd, nv_s, vp_s)
                    nv_s = nt_s.copy()
                    nv_s[kss[ij].pspin] -= ns * kss[ij].get(fg)
                    xc.calculate(gd, nv_s, vm_s)
                else:  # spin unpolarised
                    nv = nt_s + ns * kss[ij].get(fg)
                    xc.calculate(gd, nv, vp_s)
                    nv = nt_s - ns * kss[ij].get(fg)
                    xc.calculate(gd, nv, vm_s)
                vvt_s = (0.5 / ns) * (vp_s - vm_s)
                timer2.stop()

                # initialize the correction matrices
                timer2.start('init v corrections')
                I_asp = {}
                for a, P_ni in wfs.kpt_u[kss[ij].spin].P_ani.items():
                    # create the modified density matrix
                    Pi_i = P_ni[kss[ij].i]
                    Pj_i = P_ni[kss[ij].j]
                    P_ii = np.outer(Pi_i, Pj_i)
                    # we need the symmetric form, hence we can pack
                    P_p = pack(P_ii)
                    D_sp = self.paw.density.D_asp[a].copy()
                    D_sp[kss[ij].pspin] -= ns * P_p
                    setup = wfs.setups[a]
                    I_sp = np.zeros_like(D_sp)
                    self.xc.calculate_paw_correction(setup, D_sp, I_sp)
                    I_sp *= -1.0
                    D_sp = self.paw.density.D_asp[a].copy()
                    D_sp[kss[ij].pspin] += ns * P_p
                    self.xc.calculate_paw_correction(setup, D_sp, I_sp)
                    I_sp /= 2.0 * ns
                    I_asp[a] = I_sp
                timer2.stop()

            timer.stop()
            t0 = timer.get_time('init')
            timer.start(ij)

            for kq in range(ij, nij):
                weight = self.weight_Kijkq(ij, kq)

                if self.derivativeLevel == 0:
                    # only Exc is available

                    if kss.npspins == 2:  # spin polarised
                        nv_g = nt_sg.copy()
                        nv_g[kss[ij].pspin] += kss[ij].get(fg)
                        nv_g[kss[kq].pspin] += kss[kq].get(fg)
                        Excpp = xc.get_energy_and_potential(
                            nv_g[0], v_g, nv_g[1], v_g)
                        nv_g = nt_sg.copy()
                        nv_g[kss[ij].pspin] += kss[ij].get(fg)
                        nv_g[kss[kq].pspin] -= kss[kq].get(fg)
                        Excpm = xc.get_energy_and_potential(
                            nv_g[0], v_g, nv_g[1], v_g)
                        nv_g = nt_sg.copy()
                        nv_g[kss[ij].pspin] -=\
                            kss[ij].get(fg)
                        nv_g[kss[kq].pspin] +=\
                            kss[kq].get(fg)
                        Excmp = xc.get_energy_and_potential(
                            nv_g[0], v_g, nv_g[1], v_g)
                        nv_g = nt_sg.copy()
                        nv_g[kss[ij].pspin] -= \
                            kss[ij].get(fg)
                        nv_g[kss[kq].pspin] -=\
                            kss[kq].get(fg)
                        Excpp = xc.get_energy_and_potential(
                            nv_g[0], v_g, nv_g[1], v_g)
                    else:  # spin unpolarised
                        nv_g = nt_sg + ns * kss[ij].get(fg)\
                            + ns * kss[kq].get(fg)
                        Excpp = xc.get_energy_and_potential(nv_g, v_g)
                        nv_g = nt_sg + ns * kss[ij].get(fg)\
                            - ns * kss[kq].get(fg)
                        Excpm = xc.get_energy_and_potential(nv_g, v_g)
                        nv_g = nt_sg - ns * kss[ij].get(fg)\
                            + ns * kss[kq].get(fg)
                        Excmp = xc.get_energy_and_potential(nv_g, v_g)
                        nv_g = nt_sg - ns * kss[ij].get(fg)\
                            - ns * kss[kq].get(fg)
                        Excmm = xc.get_energy_and_potential(nv_g, v_g)

                    Om_xc[ij, kq] += weight *\
                        0.25 * \
                        (Excpp - Excmp - Excpm + Excmm) / (ns * ns)

                elif self.derivativeLevel == 1:
                    # vxc is available

                    timer2.start('integrate')
                    Om_xc[ij, kq] += weight *\
                        self.gd.integrate(kss[kq].get(fg) *
                                          vvt_s[kss[kq].pspin])
                    timer2.stop()

                    timer2.start('integrate corrections')
                    Exc = 0.
                    for a, P_ni in wfs.kpt_u[kss[kq].spin].P_ani.items():
                        # create the modified density matrix
                        Pk_i = P_ni[kss[kq].i]
                        Pq_i = P_ni[kss[kq].j]
                        P_ii = np.outer(Pk_i, Pq_i)
                        # we need the symmetric form, hence we can pack
                        # use pack as I_sp used pack2
                        P_p = pack(P_ii)
                        Exc += np.dot(I_asp[a][kss[kq].pspin], P_p)
                    Om_xc[ij, kq] += weight * self.gd.comm.sum(Exc)
                    timer2.stop()

                elif self.derivativeLevel == 2:
                    # fxc is available
                    if kss.npspins == 2:  # spin polarised
                        Om_xc[ij, kq] += weight *\
                            gd.integrate(kss[ij].get(fg) *
                                         kss[kq].get(fg) *
                                         fxc_sg[kss[ij].pspin, kss[kq].pspin])
                    else:  # spin unpolarised
                        Om_xc[ij, kq] += weight *\
                            gd.integrate(kss[ij].get(fg) *
                                         kss[kq].get(fg) *
                                         fxc_sg)

                    # XXX still numeric derivatives for local terms
                    timer2.start('integrate corrections')
                    Exc = 0.
                    for a, P_ni in wfs.kpt_u[kss[kq].spin].P_ani.items():
                        # create the modified density matrix
                        Pk_i = P_ni[kss[kq].i]
                        Pq_i = P_ni[kss[kq].j]
                        P_ii = np.outer(Pk_i, Pq_i)
                        # we need the symmetric form, hence we can pack
                        # use pack as I_sp used pack2
                        P_p = pack(P_ii)
                        Exc += np.dot(I_asp[a][kss[kq].pspin], P_p)
                    Om_xc[ij, kq] += weight * self.gd.comm.sum(Exc)
                    timer2.stop()

                if ij != kq:
                    Om_xc[kq, ij] = Om_xc[ij, kq]

            timer.stop()
# timer2.write()
            if ij < (nij - 1):
                print('XC estimated time left',
                      self.time_left(timer, t0, ij, nij), file=self.txt)
    def get_rpa(self):
        """Calculate RPA and Hartree-fock part of the A+-B matrices."""

        # shorthands
        kss = self.fullkss
        finegrid = self.finegrid

        # calculate omega matrix
        nij = len(kss)
        print("RPAhyb", nij, "transitions", file=self.txt)

        AmB = np.zeros((nij, nij))
        ApB = self.ApB

        # storage place for Coulomb integrals
        integrals = {}

        for ij in range(nij):
            print("RPAhyb kss[" + "%d" % ij + "]=", kss[ij], file=self.txt)

            timer = Timer()
            timer.start("init")
            timer2 = Timer()

            # smooth density including compensation charges
            timer2.start("with_compensation_charges 0")
            rhot_p = kss[ij].with_compensation_charges(finegrid is not 0)
            timer2.stop()

            # integrate with 1/|r_1-r_2|
            timer2.start("poisson")
            phit_p = np.zeros(rhot_p.shape, rhot_p.dtype)
            self.poisson.solve(phit_p, rhot_p, charge=None)
            timer2.stop()

            timer.stop()
            t0 = timer.get_time("init")
            timer.start(ij)

            if finegrid == 1:
                rhot = kss[ij].with_compensation_charges()
                phit = self.gd.zeros()
                self.restrict(phit_p, phit)
            else:
                phit = phit_p
                rhot = rhot_p

            for kq in range(ij, nij):
                if kq != ij:
                    # smooth density including compensation charges
                    timer2.start("kq with_compensation_charges")
                    rhot = kss[kq].with_compensation_charges(finegrid is 2)
                    timer2.stop()
                pre = self.weight_Kijkq(ij, kq)

                timer2.start("integrate")
                I = self.Coulomb_integral_kss(kss[ij], kss[kq], phit, rhot)
                if kss[ij].spin == kss[kq].spin:
                    name = self.Coulomb_integral_name(kss[ij].i, kss[ij].j, kss[kq].i, kss[kq].j, kss[ij].spin)
                    integrals[name] = I
                ApB[ij, kq] = pre * I
                timer2.stop()

                if ij == kq:
                    epsij = kss[ij].get_energy() / kss[ij].get_weight()
                    AmB[ij, kq] += epsij
                    ApB[ij, kq] += epsij

            timer.stop()
            # timer2.write()
            if ij < (nij - 1):
                print("RPAhyb estimated time left", self.time_left(timer, t0, ij, nij), file=self.txt)

        # add HF parts and apply symmetry
        if hasattr(self.xc, "hybrid"):
            weight = self.xc.hybrid
        else:
            weight = 0.0
        for ij in range(nij):
            print("HF kss[" + "%d" % ij + "]", file=self.txt)
            timer = Timer()
            timer.start("init")
            timer.stop()
            t0 = timer.get_time("init")
            timer.start(ij)

            i = kss[ij].i
            j = kss[ij].j
            s = kss[ij].spin
            for kq in range(ij, nij):
                if kss[ij].pspin == kss[kq].pspin:
                    k = kss[kq].i
                    q = kss[kq].j
                    ikjq = self.Coulomb_integral_ijkq(i, k, j, q, s, integrals)
                    iqkj = self.Coulomb_integral_ijkq(i, q, k, j, s, integrals)
                    ApB[ij, kq] -= weight * (ikjq + iqkj)
                    AmB[ij, kq] -= weight * (ikjq - iqkj)

                ApB[kq, ij] = ApB[ij, kq]
                AmB[kq, ij] = AmB[ij, kq]

            timer.stop()
            if ij < (nij - 1):
                print("HF estimated time left", self.time_left(timer, t0, ij, nij), file=self.txt)

        return AmB