CASINO manual - Theory of Condensed Matter

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should pick out random.log files from different stages of a calculation (e.g., VMC configuration generation / DMC equilibration / DMC statistics accumulation) and rename them appropriately. Since 1.2011 (for more than 100 processors) the check on random seeds being equal on different processors is only performed when RANPRINT is greater than zero. REDIST GRP SIZE (Integer) In the branch-and-redistribute algorithm (which does redistribution of configurations across nodes in DMC), we must decide which pairs of nodes are involved in configuration transfers, and how many configurations are to be transferred in each operation. There is an optimal algorithm for doing this (involving looking at individual configuration multiplicities and the exact excess or deficit of configurations relative to a target on each node. If we consider all the nodes then this algorithm scales linearly with the number of nodes, eventually becoming so expensive that for a fixed number of configurations the code actually becomes slower if we increase the number of nodes. We therefore parallelize the algorithm; to do this we form groups of processors (‘redist groups’) of size redist grp size (plus some remainder). When calculating the vector of instructions, only transfers within these groups are contemplated, and the cost for working out what to send where no longer increases with the number of nodes (above a certain size). RELATIVISTIC (Logical) If relativistic is T, then relativistic corrections to the energy are calculated using perturbation theory. Note that this can only be done for closed-shell systems at present. See Sec. 32 for further details. RNG RESTART SAFE (Logical) We would like, e.g., a 1000-move VMC run, and two 500-move VMC runs linked together by a restart to give the same answer, in the sense that we end up with the same vmc.hist file. Unfortunately they do not in general since the pseudorandom number sequence is affected by the restart. This is because random numbers are generated something like 63 at a time and stored in a buffer until needed (this buffer being refilled when necessary). In the normal way of saving a point in the random number sequence, any unused numbers in the buffer are discarded, which means the final answer will be different to the unrestarted case. If the keyword rng restart safe is T (which is actually now the default) then the whole current buffer is saved in the final config.out file as well as the current state of the random sequence (necessarily fixed at the end of the current buffer). This allows multiple step runs to give the same answer as single step runs, at the expense of slightly larger configuration files. RUNTYPE (Text) This keyword specifies the type of QMC run to be carried out. It can take the following values: ‘vmc’ (perform a single VMC simulation); ‘dmc equil’ (perform DMC equilibration); ‘dmc stats’ (perform DMC statistics accumulation); ‘dmc’ (perform DMC equilibration, then statistics accumulation); ‘vmc dmc’ (perform VMC, then DMC equilibration, then DMC statistics accumulation); ‘vmc dmc equil’ (perform VMC, then DMC equilibration); ‘opt’ (perform a single wave-function optimization calculation); ‘vmc opt’ (perform opt cyles cycles of VMC and optimization, alternately) ‘opt vmc’ (perform opt cycles cycles of optimization and VMC, alternately); ‘gen mpc’ (generate an mpc.dat file enabling the use of the MPC interaction); ‘gen mdet casl’ (generate an mdet.casl file for use by the det compress utility); ‘plot’ (perform plot specified by block qmc plot). NOTE: in earlier versions of the code, we used ‘runtype : dmc’ with the now-redundant keyword ‘iaccumulate : T or F’ to indicate whether stats accumulation was activated or not. This usage is now deprecated and, unless iaccumulate is specifically defined in input, then ‘runtype : dmc’ is just a synonym for ‘runtype : dmc dmc’. SCELL MATRIX (Block) If the simulation-cell lattice vectors are {a i } and the primitive-cell lattice vectors are {p j } then we may write a i = ∑ j S ijp j , where the S ij are integers. The 3 × 3 integer matrix S is given in the scell matrix input block. This is a generalization of npcell (which simply gives the diagonal elements of S in the special case that S is diagonal). Only one of npcell and scell matrix should be present in the input file. SHM SIZE NPROC (Integer) In Shm calculations on Blue Gene machines one needs to know in advance the number of MB of shared memory required, so that one may set the BG SHAREDMEMSIZE environment variable (which can be done by means of the --user.shemsize argument to runqmc). casino will calculate this number and print it to output at the end of the setup process (within the scope of testrun=T). However, the amount of shared memory required depends on the number of cores (or the number of MPI processes if running more or less than one process per core). If one ultimately wishes to run on, say, 52
half a million cores, it may be desirable to execute the test run on just a few cores on your personal laptop, rather than waiting a week for the full job to sit in a queue. For the purposes of computing the size of the shared memory partition, one may therefore set the number of desired processes by setting shm size nproc, and this value will be used in the computation of the shared memory size rather than the actual number of cores being used in the test run (unless shm size nproc=0 - which is the default). Note that the casino test run must be done in Shm mode. SMALL TRANSFER (Logical) If small transfer is set to T, the DBAR matrices and any potentially large optional data are not transferred across nodes in DMC configuration redistribution. The default is F. Set to T if you run into problems with parallel transfers. SPARSE (Logical) casino is capable of using sparse matrix algebra in some algorithms for efficiency purposes. For systems which are definitely not sparse (orbitals not well localized) then attempting to use sparse algorithms might actually slow things down. Thus, until we work out a better way, you can toggle this behaviour with the sparse flag. In these algorithms a matrix element is considered to be zero if it less than the value of the input keyword sparse threshold. SPARSE THRESHOLD (Real) casino sometimes uses sparse matrix algebra for efficiency purposes. In a future version, matrix elements will be taken to be zero if they are less than sparse threshold. This keyword has no effect at present, however. SP BLIPS (Logical) The single-particle orbitals that appear in the determinants can require a great deal of memory when expanded in a blip basis. When sp blips=T, casino represents the blip coefficients using single-precision real or complex numbers, which will halve the memory required. This parameter is only relevant when atom basis type=‘blip’. The default value is F. SPIN DENSITY (Logical) Setting spin density to T will activate the accumulation of separate up- and down-spin densities in the expval.data file. (This can only be done for periodic systems and finite single atoms at the moment; the finite molecule case has not been implemented.) See Sec. 33. SPLOT (Logical) If splot is T then the line plotter will use just the s component of orbitals. Useful for analysing Gaussian cusp corrections (see Sec. 16). STRUC FACTOR SPH (Logical) If structure factor sph is set to T then the spherically averaged structure factor will be accumulated in the expval.data file (homogeneous systems only). See Sec. 33. STRUCTURE FACTOR (Logical) If structure factor is set to T then the structure factor will be accumulated in the expval.data file (periodic systems only). See Sec. 33. TESTRUN (Logical) If this flag is T then casino will read input files, print information and stop. TIMING INFO (Logical) Setting timing info to F (the default) will turn off the collection of subroutine timings. You might want to do this as the timing routines can adversely affect system performance on certain computers (such as Alpha or PC clusters), especially for small systems. See Appendix A.4. TPDMC (Integer) tpdmc (T p ) is the number of time steps for which the effects of changes in the (theoretically constant) reference energy should be undone in order to estimate the DMC energy at a given point. It is assumed that the best estimates of the DMC energy separated by an amount greater than this are not correlated by fluctuations in the reference energy. Thus T p should exceed the timescale of fluctuations in the reference energy. A suggested value is T p = 10/τ, where τ is the time step. If you set it to 9999 in the input, then the code will automatically use this value; if you set it to 0 then the reweighting scheme for populationcontrol biasing will not be used. The latter is the default since time-step bias is generally not a problem in practice, and the reweighting scheme is an additional source of noise. See Sec. 13.7. TWOP DENSITY MAT (Logical) If twop density mat is set to T, then the spherically averaged diagonal term of the two-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, and will increase the cost of the calculation significantly. See Sec. 33. 53
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CASINO User’s Guide Version 2.13
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8.6 GAUSSIAN94/98/03/09 . . . . . .
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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 and 54: MOVIECELLS (Logical) If F then casi
Page 55 and 56: OPT MAXITER (Integer) Largest permi
Page 57: of G vectors and discards all those
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
Page 105 and 106: total weight must always be include
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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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