CASINO manual - Theory of Condensed Matter

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38.3 DMC in parallel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 38.4 Scaling of the DMC algorithm with the number of processors . . . . . . . . . . . . . . 208 39 OpenMP support 210 39.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 39.2 Implementation basics and performance . . . . . . . . . . . . . . . . . . . . . . . . . . 211 39.3 Using OpenMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Appendices 211 A Appendix 1: Programming guide for CASINO 211 A.1 Style . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 A.2 Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 A.3 Testing and debugging CASINO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 A.4 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 A.5 Bug reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 A.6 Requests for new features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 B Appendix 2: Automatic testing of CASINO 217 B.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 B.2 Running the set of examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 B.3 Adding a new example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 B.4 Using git-bisect with autotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 C Appendix 3: Converting CASINO v1.x input files to CASINO v2.x format 218 D Appendix 4: Specification of the format of the correlation.data file 219 E Appendix 5: CASINO system-specific data files 220 Bibliography 230 6
1 Introduction casino is a computer program system for performing quantum Monte Carlo (QMC) electronic structure calculations that has been developed by members of the Theory of Condensed Matter group in the Cambridge University physics department, and their collaborators, over more than 20 years. It is capable of calculating incredibly accurate solutions to the Schrödinger equation of quantum mechanics for realistic systems built from atoms. Other highly accurate methods are known that can do this of course, but what makes casino important is that given a big enough computer it can carry on doing this for systems containing hundreds or even thousands of atoms. These many atoms can form isolated giant molecules or groups of molecules, or they can be the repeating unit in an infinite crystal periodic in one, two, or three dimensions. Because of their inferior scaling with system size, competing methods of comparable accuracy generally struggle to handle more than a few tens of atoms. casino is also important because QMC is one of the few methods genuinely capable of exploiting the power of modern computer hardware. Modern versions of casino, by contrast, have been shown to exhibit essentially perfect parallel efficiency on machines with hundreds of thousands of cores in all of its various modes of operation. The QMC research program that culminated in casino as we know it today was begun in the early 1990s by Richard Needs, who had obtained inspiration from a short period working in the United States. He developed his initial ideas in collaboration with Guna Rajagopal and Matthew Foulkes and a number of early postdocs and students. Their initial test codes were gathered together and generalized into the first QMC program capable of treating any arbitrary system (named ‘casino’ after a suggestion from Paul Kent) by Mike Towler, who had arrived in Cambridge in late 1996. The first public version of casino was published in 1999. Absolutely fundamental improvements and generalizations of the code were made by Neil Drummond (from 2002) and Pablo López Ríos (from 2004). Needs, Towler, Drummond and López Ríos are now considered to be principal authors of the code, and all four of them continue to be at the heart of the project today. Over the years, valuable additional contributions to the software base have been made by students, postdocs, and other people working in collaboration with us. A reasonably complete set would include Andrew Porter, Randy Hood, Andrew Williamson, Dario Alfè, Gavin Brown, Chris Pickard, Rene Gaudoin, Ben Wood, Zoltán Radnai, Andrea Ma, Ryo Maezono, John Trail, Paul Kent, Nick Hine, Alexander Badinski, Matthew Brown, Ken Esler, Andrew Morris, Norbert Nemec, Robert Lee, Priyanka Seth, Bohshiang Jong, Lucian Anton, Katie Schwarz, Pascal Bugnion, and Elaheh Mostaani. The following citation (quoted in full) is required in any publication describing results obtained with casino: R. J. Needs, M. D. Towler, N. D. Drummond and P. López Ríos, J. Phys.: Condens. Matter 22, 023201 (2010). Further public information and resources—including forms for downloading the code—are available at the casino web page: http://vallico.net/casinoqmc 1
Page 1 and 2: CASINO User’s Guide Version 2.13
Page 3 and 4: 8.6 GAUSSIAN94/98/03/09 . . . . . .
Page 5: 29.2 Fourier transformation of CASI
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
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of G vectors and discards all those
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half a million cores, it may be des
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VM REWEIGHT (Logical) If vm reweigh
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default this is 0 hartree. It shoul
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A very detailed specification of th
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-1 0 0 1 1 1 1 1 1 1 0 2 1 0 1 2 Pa
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cusp conditions; otherwise, only th
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Detailed information about each of
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|k| (outermost). Hence one can spec
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large and the wave function is near
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R(i) in atomic units 0.000000000000
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2. The charge-density Fourier coeff
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c_767: [ 996 ] ... Compressed expan
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valence charges for each atom %%%%%
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1988). This can be found online. An
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1.3813695578425E+00 1.3957621401173
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PWSCF Method: DFT DFT Functional: u
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0.125203784849961E-01 0.13042462855
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3.3000000000000E+00 2.0000000000000
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Potential Number of grid points 200
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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
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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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