CASINO manual - Theory of Condensed Matter

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ESUPERCELL (Logical) By default total energies and their components in periodic systems are printed as energies per primitive cell. Switching this flag to T forces printing of energies per simulation cell in the output file. EWALD CHECK (Logical) casino and the wave-function generating program should be able to calculate the same value for the nuclear repulsion energy, given the same crystal structure. By default casino computes the Ewald interaction and compares it with the value given in the wave-function file. If they differ by more than 10 −5 , then casino will stop and complain. If you have a justifiable reason for doing so (e.g., you have turned off periodicity), you may turn off this check by setting ewald check to F. EWALD CONTROL (Real) This is the percentage increase (from the default) of the cutoff radius for the reciprocal space sum in the Ewald interaction, which is used for calculating electrostatic interactions between particles in periodic systems. Its default value is zero. Increasing ewald control will cause more vectors to be included in the sum, the effect of which is to increase the range of the Ewald γ parameter over which the energy is constant (the default γ should lie somewhere in the middle of this range). This need only be done in exceptional circumstances and the default should be fine for the general user. See Sec. 19.4 for information about the Ewald method. EXPOT (Logical) If expot is set to T then an external potential is read from the file expot.data and included as a summed contribution to the total energy. See Sec. 7.9. EXPVAL CUTOFF (Physical) expval cutoff is the energy cutoff for G-vectors used in the evaluation of expectation values accumulated in reciprocal space (e.g., the density, spin density, pair-correlation function, etc.). The value of expval cutoff is ignored if an expval.data file is already present, in which case the G-vector set(s) given therein are used instead. If you set it to zero, then the program will suggest a value. The default is 3 a.u. See Sec. 7.11. EXPVAL ERROR BARS (Logical) If this flag is set, casino will, where practicable, accumulate the additional quantities required to evaluate error bars on requested expectation values. This will increase the size of the expval.data file and slow down the calculation slightly. At present this functionality is limited to the structure factor. EXPVAL KGRID (Block) This block contains a specification of one or more k-point grids defined in one, two or three dimensions. A one-dimensional grid is defined by a line AB, a two-dimensional grid by a plane AB–AC and a three-dimensional grid by a parallelepiped AB–AC–AD, together with an appropriate number of k-points along each direction. These grids may be used in the calculation of various expectation values, if the appropriate keywords are set to T in input. The block consists of the following lines: Line 1: Number of grids defined in this block; Line 2: Which expectation value uses this grid? (2 for spherical structure factor); Line 3: Dimensionality d of current k-grid (1–3); Line 4: Coordinates of k-point A (a.u.); Line 5: Coordinates of k-point B (a.u.), number of points along AB; Line 6: [If d = 2 or 3] Coordinates of k-point C (a.u.), number of points along AC; Line 7: [If d = 3] Coordinates of k-point D (a.u.), number of points along AD. Repeat lines 2 to 7 for each additional grid. Note that spherically averaged quantities require a one-dimensional grid, irrespective of the dimensionality of the system. FINITE SIZE CORR (Logical) Calculate finite-size corrections to the kinetic energy and the electron–electron interaction energy in periodic systems using the method described in Ref. [17]. See Secs. 29 and 30 for further information. FIX HOLES (Logical) This keyword is used to define the reference points for the exciton-exciton separation when using the ‘BIEX3’ wave function. Setting fix holes to T means that the two holes are fixed at a distance xx sep apart. The default is F, in which case the centres of mass of the two excitons are fixed instead. If BIEX3 is not being used then this keyword is ignored. FORCES (Logical) Calculate atomic forces in VMC/DMC. Forces are only implemented for Gaussian basis sets and only work in pseudopotential calculations (in order to eliminate the electron– nucleus singularity). 42
FORCES INFO (Integer) Controls the amount of information calculated/displayed during force calculations: ‘2’: display no additional information; the Hellmann–Feynman force is evaluated with the d- channel of the pseudopotential chosen to be local and the s-d and p-d channels nonlocal (default); ‘5’: calculate and display two additional Hellmann–Feynman force estimators, where the s- and p-channels of the pseudopotential components are chosen to be local. FREE PARTICLES (Block) This block sets the parameters that define the behaviour of the orbitals which are not atom-related in a system. The geometry of the system can be given using ‘r s 〈r s 〉’, ‘dimensionality 〈d〉’ and ‘cell geometry’ (followed by d lines with d reals corresponding to the unscaled cell vectors). For 2D or 1D systems one can also specify that the electrons are confined to different layers (wires in 1D) using ‘heg nlayers 〈no. layers〉’ and ‘heg zlayer 〈layer〉〈z〉’, with species being assigned to layers using ‘heg layer 〈spin〉〈layer〉’. In 1D, one can also specify the y-coordinate of a wire using ‘heg ylayer 〈layer〉〈y〉’. These parameters are only required if atom basis type=‘none’ (which it is by default) in the input file). The number and type of the orbitals can be given using lines with the syntax ‘particle 〈i〉 det 〈det〉 : 〈n〉 orbitals 〈orb〉 [orb-options]’, where 〈det〉 is the term in the multideterminant expansion, 〈i〉 must be 1, 2 or a number given in the particles block (1 and 2 are up- and down-spin electrons), 〈n〉 is the number of free particles/orbitals belonging to the 〈det〉th determinant and ‘〈orb〉 [orb-options]’ is one of the following: ‘free’, ‘crystal sublattice 〈s〉’, ‘pairing 〈j〉’, ‘sdw’ or ‘expot 〉set〈’, 〈j〉 being the particle type with which 〈i〉 is paired and 〉set〈 being an orbital set in expot.data. If the orbitals have optimizable parameters, these must be provided in correlation.data. Wigner-crystal geometry is specified using the keywords ‘crystal type 〈type〉〈n〉 sublattice[s] [repeat 〈r〉]’ (type = ‘cubic’, ‘fcc’, ‘bcc’, ‘rectangular’, ‘hexagonal’ or ‘triangular’, which must match ‘dimensionality’ and ‘cell geometry’, or ‘manual’), and ‘sublattice 〈s〉 [antiferro[magnetic]] offset 〈x y z〉’ for predefined lattices, and ‘sublattice 〈s〉 manual 〈n〉 site[s]’ followed by 〈n〉 lines of the form 〈x y z〉 defining the sites for manual lattices. If a complex wave function is used, i.e., complex wf is set to T, then an offset to the grid of k vectors for fluid phases may be specified using ‘k offset 〈k x 〉〈k y 〉〈k z 〉’, where k x , k y and k z are the Cartesian components of the offset. The offset is translated into the first Brillouin zone of the simulation cell. Using a nonzero offset corresponds to using twisted boundary conditions. It’s not quite as difficult to use this input block as it may appear from the above: see the examples in ~/CASINO/examples/electron phases and ~/CASINO/examples/electron hole phases. FUTURE WALKING (Logical) If this flag is set to T then future walking will be used to evaluate pure estimators in DMC. See Sec. 35. GAUTOL (Real) Tolerance for Gaussian orbital evaluation. neglected if its value is less than 10 −gautol . The contribution of a Gaussian is GROWTH ESTIMATOR (Logical) Turn on calculation of the growth estimator of the total energy in DMC calculations. A statistically significant difference between the mixed estimator and the growth estimator for the energy normally implies the presence of time-step bias. Other than that, the growth estimator is not generally useful, because the statistical error in the growth estimator is substantially greater than the error in the mixed estimator. See Sec. 13.8 for more information. HAVE AE (Logical) If have ae is F, casino expects to find pseudopotentials for all nuclei in the system. The default value is guessed from the basis type (blip and plane-wave orbitals: F; numerical and slater-type orbitals: T; Gaussian orbitals: depends on whether pseudo-ions with Z > 200 are present). Only in exceptional cases will it be necessary to set have ae explicitly. If all-electron ions and pseudo-ions are present, both have ae and allow ae ppots need to be set to T. IBRAN (Logical) If set to T then weighting and branching is allowed in DMC. Setting ibran=F may be used to check the DMC algorithm, as it then reduces to a VMC algorithm in which the DMC drift-diffusion Green’s function is the transition probability density. INITIAL CONFIG (Block) Use this keyword if you want to specify the initial VMC configuration to use instead of the random one generated by the points routine. It is possible to specify the positions of only some of the particles. The format of each line in this block is: σ i x y z 43
Page 1 and 2: CASINO User’s Guide Version 2.13
Page 3 and 4: 8.6 GAUSSIAN94/98/03/09 . . . . . .
Page 5 and 6: 29.2 Fourier transformation of CASI
Page 7 and 8: 1 Introduction casino is a computer
Page 9 and 10: 3.2 Legal stuff casino is given awa
Page 11 and 12: - Grossman-Mitas DMC-DFT molecular
Page 13 and 14: Your defined setup can then be perm
Page 15 and 16: - : perform compilation (default).
Page 17 and 18: 6 Introductory user’s guide: how
Page 19 and 20: ATOM BASIS TYPE The basis used to r
Page 21 and 22: ENVMC v0.60: Script to extract VMC
Page 23 and 24: Std. err. in the mean DMC energy (a
Page 25 and 26: Jastrow factor from each cycle of t
Page 27 and 28: V(x) Ψ init (x) τ{ t Ψ 0 (x) x T
Page 29 and 30: the energy becomes roughly constant
Page 31 and 32: many cores, time limits etc, which
Page 33 and 34: Set the verbosity level of the mach
Page 35 and 36: 6.7 How to run coupled DFT-DMC mole
Page 37 and 38: unqmcmd --startqmc=M Start the chai
Page 39 and 40: config.out This is the name under w
Page 41 and 42: ‘slater-type’: use Slater-type
Page 43 and 44: CUSTOM SPAIR DEP (Block) This input
Page 45 and 46: initial configurations come from DM
Page 47: DTDMC (Real) Time step for DMC run
Page 51 and 52: nucleus is assumed to lie at the or
Page 53 and 54: MOVIECELLS (Logical) If F then casi
Page 55 and 56: OPT MAXITER (Integer) Largest permi
Page 57 and 58: of G vectors and discards all those
Page 59 and 60: half a million cores, it may be des
Page 61 and 62: VM REWEIGHT (Logical) If vm reweigh
Page 63 and 64: default this is 0 hartree. It shoul
Page 65 and 66: A very detailed specification of th
Page 67 and 68: -1 0 0 1 1 1 1 1 1 1 0 2 1 0 1 2 Pa
Page 69 and 70: cusp conditions; otherwise, only th
Page 71 and 72: Detailed information about each of
Page 73 and 74: |k| (outermost). Hence one can spec
Page 75 and 76: large and the wave function is near
Page 77 and 78: R(i) in atomic units 0.000000000000
Page 79 and 80: 2. The charge-density Fourier coeff
Page 81 and 82: c_767: [ 996 ] ... Compressed expan
Page 83 and 84: valence charges for each atom %%%%%
Page 85 and 86: 1988). This can be found online. An
Page 87 and 88: 1.3813695578425E+00 1.3957621401173
Page 89 and 90: PWSCF Method: DFT DFT Functional: u
Page 91 and 92: 0.125203784849961E-01 0.13042462855
Page 93 and 94: 3.3000000000000E+00 2.0000000000000
Page 95 and 96: Potential Number of grid points 200
Page 97 and 98: 9. Clearly, the total number of pos
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EBEST (DMC only) Best estimate of t
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Use G-vector set 1 Number of sets 2
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1000.0 rho_a(G)*rho_b(-G) 16.0 4.12
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total weight must always be include
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The exporter does not currently wor
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8.4.2 Generating gwfn.data files wi
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After successfully running properti
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% mv Test.FChk dna.Fchk run gaussia
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• By default, gaussian uses spin
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Routine Purpose qmc write Writes th
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not the case the defaults can be ch
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8.10 TURBOMOLE Website: www.turbomo
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• crysgen06/09, crystaltoqmc: The
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• quickblock: Simple reblocking u
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• In Movie Settings choose Trajec
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the move rejection probability is h
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This leads to the single-electron d
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In the UNR [19] scheme the modified
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13.7 Evaluating expectation values
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Population-control catastrophes sho
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where u k has the periodicity of th
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Although the constraint equations a
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18 Wave-function updating Consider
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19.2 Evaluating the nonlocal pseudo
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of a unit point charge at r j in ev
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19.4.3 1D Coulomb interaction Coulo
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To investigate whether the extrapol
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correlations, such as might be enco
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where n is the order of the expansi
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terms by definition, and it can be
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which is therefore independent of r
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where the local energy, E L , is E
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Another variant of variance minimiz
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The energy minimization method used
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valid. The first problem, which ari
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• Is emin min energy too high? Th
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It may be activated by setting vmc
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that the number of configuration mo
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• It is possible to use blip orbi
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0.5 0.5 0.0 particle 1 det 1 : 9 or
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The clearup twistav script can be u
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In the infinite system limit, the s
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Note that this has the k −2 diver
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• The effective time step, Eq. (3
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1 2 H He 1.00794 4.00260 3 4 5 6 7
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and the Dirac delta function is δ(
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33.2.2 Atomic densities K eywords:
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The spin-density matrix is a two-by
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33.3.3 Homogeneous and isotropic sy
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33.4 Structure factor and spherical
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33.5 One-body density matrix, two-b
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[ where the approximation ρ (1)T
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The figure shows the localization l
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with F HFT mix = − F P mix = −
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The input keyword to activate the c
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To each walker r j , we assign a li
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37 Magnetic fields and the fixed-ph
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38 Analysis of the performance of C
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the orbitals, α = 2 [11]. The use
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39.2 Implementation basics and perf
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• Use ‘endif’ and ‘enddo’
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• Evidence of testing on serial a
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B Appendix 2: Automatic testing of
Page 225 and 226:
• Delete any eepot.data and densi
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* "Generic" CASINO_ARCHs are intend
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- ‘head -n 1 /etc/redhat-release
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for a single job in an ensemble of
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inary executable. CASINO does not r
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otherwise. The following tags are o
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[2] V.R. Saunders, R. Dovesi, C. Ro
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[50] W. Janke, Statistical Analysis
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CASINO manual - Theory of Condensed Matter

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