performs simulated annealing on the magnetic structure stat = ANNEAL(obj, 'option1', value1 ...) The function can deal only with single ion anisotropy and isotropic exchange interactions in 1, 2 or 3 spin dimensions. General and antisymmetric exchage interactions are not supported yet! Also the g-tensor is fixed to 2. WARNING! The calculated energies doesn't contain the self energy (moment coupled to itself), thus the energies calculated here can differ from the result of the sw.energy() function. Input: obj Input object contains structural data, sw type. Options: spinDim Dimensionality of the magnetic moments. 1 Ising spins 2 XY spins 3 Heisenberg spins [default] For Ising (spinDim=1) and XY (spinDim=2) models only isotropic exchange interaction and magnetic field can be used. For Ising the direction of the spins are along x-axis, for XY model the the xy-plane. Magnetic fields perpendicular to these directions are omitted. initT The initial temperature, can be any positive number, unit is Kelvin. Default is 1. endT Temperature at which to stop, can be any positive number smaller than 'InitTemp', unit is Kelvin. Default is 1e-3. cool Generates a new temperature from the previous one. Any function handle that takes a scalar as input and returns a smaller but positive scalar as output. Default is @(T) (.92*T). random Random initial conditions, if initial spin configuration is undefined (obj.mag_str.S is empty) the initial configuration is automaticly random independently of the value of random. Default is false. nMC Number of Monte-Carlo steps per spin at each temperature step to reach thermal equilibrium. Default is 100. nORel Number of over-relaxation steps after every Monte-Carlo steps. It rotates the spins around the direction of the local field by 180deg. It is reversible and microcanonical if the single ion anisotropy is zero. Default is 0. nStat Number of cycles at the last temperature to calculate statistical averages. It has to be smaller or equal nMC. Default is 100. boundary Boundary conditions of the extended unit cell. 'free' Free, interactions between extedned unit cells are omitted. 'per' Periodic, interactions between extended unit cells are retained. Default is {'per' 'per' 'per'}. verbosity Controls output to the screen. 0 suppresses all output 1 gives final report only 2 plots temperature changes and final report [default] nExt The size of the magnetic cell in number of unit cells, to provide input information to 'fStat'. Default is from obj.mag_str.N_ext. fStat Function handle to evaluate after at the end of the cooling scedule during the last nStat Monte-Carlo steps. The function returns a single structure and takes fixed input parameters: struct = fStat(state, struct, T, E, M, nExt). The function is called once before the annealing process when state=1 to initialise the parameters. The function is called after every Monte-Carlo steps with state=2 and the output of the previous function call is assigned to the input struct. fStat is called once again in the end with state=3 to calculate final parameters (in the last run, input struct.param contains all the annealing parameters). Default is <a href="matlab: doc sw_fstat">@sw_fstat</a>. fSub Function to define sublattices for Monte-Carlo speedup. cGraph = fSub(conn,nExt), where cGraph is a (1,nMagExt) sized vector, conn is a (2,nConn) size matrix and nExt is equal to 'nExt'. Default is <a href="matlab: doc sw_fsub">@sw_fsub</a> subLat Vector that assigns all magnetic moments into non-interacting sublattices, contains a single index (1,2,3...) for every magnetic moment, size is (1,nMagExt). If undefined, the function defined in 'fSub' will be used to partition the lattice. title Gives a title string to the simulation that is saved in the output. autoK Bin length of the autocorrelation vector. Should be a few times smaller than nMC. Default is zero, no autocorrelation function is calculated. Output: stat Struct that contains the calculated thermodynamical averages and the parameters of the simulation with the following fields: param All input parameter values of the anneal function. obj The copy of the input sw class obj with the final magnetic structure. M Components of the magnetisation after the last annealing run, dimensions are [3 nMagExt]. E Magnetic energy of the system after the last annealing run. T Final temperature of the sample. Depending on the 'fStat' parameter, additional fields are included. Using the default function (@sw_fstat) the following parameters are calculated: avgM Average components of the magnetisation over nStat runs, dimensions are [3 nMagExt]. stdM Standard deviation of the mgnetisation components over nStat runs, dimensions are [3 nMagExt]. avgE Average system energy per spin over nStat runs, scalar. stdE Standard deviation of the system energy per spin over nStat runs, scalar. Cp Heat capacity of the sample: (<E^2>-<E>^2)/kB/T^2. Chi Magnetic susceptibility of the sample: (<M^2>-<M>^2)/kB/T. Reference: Kirkpatrick, S., Gelatt, C.D., & Vecchi, M.P. (1983). Optimization by Simulated Annealing. _Science, 220_, 671-680. See also SW, SW.OPTMAGSTR, SW_FSUB, SW_FSTAT.

- struct extracts all public properties of sw object into a struct

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