calculates dispersion and V transformation matrix using linear spin wave theory [omega, V] = CORESPEC(obj, hkl, 'option1', value1 ...) Spin wave dispersion and spin-spin correlation function is calculated at the reciprocal space points k. The function can deal with arbitrary magnetic structure and magnetic interactions as well as single ion anisotropy and magnetic field. If the magnetic ordering wavevector is non-integer, the dispersion is calculated using a coordinate system rotating from cell to cell. In this case the Hamiltonian has to fulfill this extra rotational symmetry. Input: obj Input structure, sw class object. hkl Defines the Q points where the spectra is calculated, in reciprocal lattice units, size is [3 nHkl]. Q can be also defined by several linear scan in reciprocal space. In this case hkl is cell type, where each element of the cell defines a point in Q space. Linear scans are assumed between consecutive points. Also the number of Q points can be specified as a last element, it is 100 by defaults. For example: hkl = {[0 0 0] [1 0 0] 50}, defines a scan along (h,0,0) from 0 to 1 and 50 Q points are calculated along the scan. Options: fitmode Speedup (for fitting mode only), default is false. notwin If true, the spectra of the twins won't be calculated. Default is false. sortMode The spin wave modes will be sorted if true. Default is true. optmem Parameter to optimise memory usage. The list of hkl values will be cut into optmem number of pieces and will be calculated piece by piece to decrease memory usage. Default of optmem is zero, when the number of slices are determined automatically from the available free memory. tol Tolerance of the incommensurability of the magnetic ordering wavevector. Deviations from integer values of the ordering wavevector smaller than the tolerance are considered to be commensurate. Default value is 1e-4. omega_tol Tolerance on the energy difference of degenerate modes when diagonalising the quadratic form, default is 1e-5. hermit Method for matrix diagonalization: true J.H.P. Colpa, Physica 93A (1978) 327, false R.M. White, PR 139 (1965) A450. Colpa: the grand dynamical matrix is converted into another Hermitian matrix, that will give the real eigenvalues. White: the non-Hermitian g*H matrix will be diagonalised, that is not the elegant method. Advise: Always use Colpa's method, except when small imaginary eigenvalues are expected. In this case only White's method work. The solution in this case is wrong, however by examining the eigenvalues it can give a hint where the problem is. Default is true. nSlice Parameter to optimise memory usage. The list of hkl values will be cut into nSlice pieces and will be calculated piece by piece to decrease memory usage. Default is zero, when the number of slices are determined automatically from the available free memory. onlyV Calculate only the dispersion and the V linear transformation matrices. The V matrices transform between the original magnon operators and the normal magnon operators. Output: spectra is a structure, with the following fields: omega Calculated spin wave dispersion, dimensins are [nMode nHkl], where nMagExt is the number of magnetic atoms in the extended unit cell. Sab Dynamical structure factor, dimensins are [3 3 nMode nHkl]. Each (:,:,i,j) submatrix contains the 9 correlation functions: Sxx, Sxy, Sxz, etc. V Optional output, calculated if 'onlyV' option is true (in that case Sab is not calculated). Dimensions are [nMode nMode nHkl]. nMode is the number of magnetic mode. For commensurate structures it is double the number of magnetic atoms in the magnetic cell/supercell. For incommensurate structures this number is tripled due to the appearance of the (Q+/-km) Fourier components in the correlation functions. If several twins exist in the sample, omega and Sab are packaged into a cell, that contains nTwin number of matrices. hkl Contains the input Q values, dimensins are [3 nHkl]. hklA Same Q values, but in reciproc Angstrom units in the lab coordinate system, dimensins are [3 nHkl]. incomm Whether the spectra calculated is incommensurate or not. obj The copy of the input obj. See also SW, SW.SPINWAVESYM, SW_NEUTRON, SW_POL, SW.POWSPEC, SW.OPTMAGSTR.

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