CASINO manual - Theory of Condensed Matter

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NLCUTOFFTOL (Real) This is used to define the cutoff radius for the nonlocal parts of the pseudopotential. It is defined as the maximum deviation of the nonlocal potentials from the local potential at the nonlocal cutoff radius. See Sec. 19.3. NON LOCAL GRID (Integer) non local grid selects the grid for nonlocal integration, ranging from coarse (low non local grid value) to fine (high non local grid value). The value is assumed to be the same for all atoms if it is controlled through this keyword; alternatively you can provide values of non local grid for particular species by specifying values for nlrule1 at the top of the corresponding pseudopotential files. non local grid can take values between 1 and 7, the default being 4 (used if non local grid is negative or not supplied). See Sec. 19.2 for more information. NPCELL (Block) Vector of length 3 giving the number of primitive cells in each dimension that make up the simulation cell. N.B., for the 1D-periodic case, npcell(2) and npcell(3) must be 1, and for the 2D slab case, npcell(3) must be 1. To construct more general simulation supercells, please use the scell matrix keyword. NUCLEUS GF MODS (Logical) This keyword is the switch for enabling the use of the modifications to the DMC Green’s function for the presence of bare nuclei, suggested in Ref. [19], in order to reduce time-step errors in all-electron calculations. See Sec. 13.6. ONEP DENSITY MAT (Logical) If onep density mat is set to T, then the spherically averaged one-particle density matrix will be computed and written to the expval.data file. This is only possible if the system is homogeneous for the moment. See Sec. 33. OPT BACKFLOW (Logical) Optimize backflow parameters in wave-function optimization. Sec. 23. See OPT CYCLES (Integer) Number of cycles of configuration generation and optimization to be carried out if runtype=‘vmc opt’ or ‘opt vmc’. For variance minimization, 3–6 cycles is typical; for energy minimization, 5–10 cycles is usual unless only determinant coefficients are being optimized, in which case 1–2 cycles will be enough. OPT DET COEFF (Logical) Optimize the coefficients of the determinants in wave-function optimization. OPT DTVMC (Integer) This keyword may take three possible values: opt dtvmc=0 (default) turns off optimization of the VMC time step, while opt dtvmc=1 causes the time step to be optimized during equilibration in order to achieve an acceptance ratio of (roughly) 50%. See Sec. 12.4. The value of opt dtvmc is ignored if the input block dtvmcs is supplied. casino can also maximize the diffusion constant with respect to dtvmc. This can be enabled by setting opt dtvmc=2. In a first stage, dtvmc is varied to get an acceptance ratio of 50%, so as to have decent statistics to perform the diffusion-constant maximization stage. This last option is only useful for vmc method=3, where it is the default. OPT FIXNL (Logical) If this keyword is set to T then the nonlocal energy will be fixed where possible in optimization. This is recommended for variance minimization (and T by default) as it greatly improves the speed of the optimization process, and possibly the accuracy of the optimization as well. For energy minimization, it is F by default, as the speed increase is small. OPT GEMINAL (Logical) During optimization, allow the optimization of the geminal coefficient matrix. OPT INFO (Integer) Controls amount of information displayed and/or written out during wavefunction optimization. Variance minimization: (1) display no information; (2) display energies at each function evaluation; (3) as (2), but calculate weights as well; (4) write out configurations and their energies, etc., as they are read in. Energy minimization: (1) little information; (2) basic information; (3) full information, write matrix algebra log file; (4) also write full matrices to log files; (5) also write SVD component matrices to log files, if SVD used. OPT JASTROW (Logical) Optimize the Jastrow factor in wave-function optimization. OPT MAXEVAL (Logical) Maximum number of evaluations of the variance during variance minimization (default 200). 48
OPT MAXITER (Integer) Largest permitted number of nl2sol or global EMIN iterations (default: 10). OPT METHOD (Text) There are currently four optimization methods implemented in casino: (1) variance minimization (‘varmin’); (2) minimization of the mean absolute deviation of the set of local energies from the median (‘madmin’); (3) energy minimization (‘emin’); (4) an accelerated variance minimization technique for parameters that appear linearly in the Jastrow factor (‘varmin linjas’). The first three methods are capable of optimizing the Jastrow factor, orbitals, backflow functions, and determinant coefficients. The fourth method can only be used to optimize linear parameters in the Jastrow factor. There are other keywords that affect the behaviour of each of these methods. The default value of opt method is ‘varmin’. OPT NOCTF CYCLES (Integer) Supplying a positive integer X for this keyword will cause all cutoff parameters (in the Jastrow factor, backflow function and orbital functions) to be fixed for the final X cycles of an optimization. Defaults to 0 for variance minimization, and to 50% of total cycles for energy minimization. OPT ORBITALS (Logical) Optimize parameters in the orbitals in wave-function optimization (relevant, e.g., if use orbmods=T). OPT STRICT (Logical) Setting opt strict=T will cause casino to stop a vmc opt or opt vmc run if the VMC energies are incremented within a 99.7% confidence interval during two consecutive cycles. Prevents wastage of CPU time in times of scarcity. Default value is F. ORB NORM (Real) Allows user to change normalization of orbitals by multiplying all of them by this constant. Of course this should have no effect on the energy, but it can be useful if the Slater determinant starts going singular, as it might for some very low-density systems. ORBBUF (Logical) Setting orbbuf=T turns on orbital buffering in DMC. This is an efficiency device in which buffered copies of orbitals/gradients/Laplacians are kept for later reuse. This has a significant memory cost. Orbital buffering should always be used unless you start running out of memory; hence the ability to turn it off. PAIR CORR (Logical) Set pair corr to T to accumulate the reciprocal-space pair-correlation function in the expval.data file. Currently restricted to periodic systems. Note that you also need to give the position and type of a fixed particle using the pcf rfix block (unless the density is homogeneous). See Sec. 33. PAIR CORR SPH (Logical) If pair corr sph is set to T then the spherically averaged real-space pair-correlation function will be accumulated in the expval.data file (via a process of ‘binning’ the electron-electron separations). This currently works for periodic homogeneous systems and finite isotropic systems such as electron-hole biexcitons. For periodic systems with atoms you can use the pair corr keyword instead which gives you the full (non-spherically averaged) paircorrelation function accumulated in reciprocal space. See Sec. 33. PARTICLES (Block) Using the particles block the user can define quantum particles (other than electrons, which can be introduced using neu and ned) to be used in the QMC calculation. The format of each line is ‘〈i〉〈charge/|e|〉〈mass/m e 〉〈spin/¯h〉〈name〉’. A negative value of the mass indicates that the following three lines give an anisotropic 3 × 3 mass tensor [currently unused]. casino decides whether each particle type is a fermion or a boson (based on the spin), and selects the appropriate way to combine the one-particle orbitals (symmetric combination [not currently implemented] or antisymmetric Slater determinants). The particles defined here can be assigned orbitals using the free particles block. PCF RFIX (Block) This block contains two lines. The first line gives the type of particle to be fixed during accumulation of the pair correlation function g(r, r ′ ); the second line gives the coordinates of the position r at which to fix it (in a.u.). This applies to the reciprocal-space PCF activated with the pair corr input keyword. It also applies in principle to the spherical real space PCF activated with the pair corr sph input keyword, in the sense that the format of expval.data allows it, but the accumulation of the spherical PCF with fixed particles has not yet been implemented. See Sec. 33. PERIODIC (Logical) T if and only if the system is periodic in either 1, 2 or 3 dimensions. 49
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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 and 48: DTDMC (Real) Time step for DMC run
Page 49 and 50: FORCES INFO (Integer) Controls the
Page 51 and 52: nucleus is assumed to lie at the or
Page 53: MOVIECELLS (Logical) If F then casi
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
Page 99 and 100: EBEST (DMC only) Best estimate of t
Page 101 and 102: Use G-vector set 1 Number of sets 2
Page 103 and 104: 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
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• 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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