CRYSTAL 98 1.0 February 26, 1999 V.R Saunder, R. Dovesi, C. Roetti, M. Causa, N.M. Harrison, R. Orlando, C. M. Zicovish-Wilson

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CRYSTAL 981.0February 26, 1999V.R Saunder,
R. Dovesi, C. Roetti, M. Causa, N.M. Harrison,
R. Orlando, C. M. Zicovish-Wilson

• Oleg Sychev

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Properties of interestMethods
Methods All-electrons Total-energy methods
(DFT) FLAPW, FP-LMTO, Gaussian pseudopotencial
Methods using simplifying assumptions for the
crystal potencial LMTO-ASA, ASW Semiempirical
methods Classical molecular dynamics model
Hamiltonians

• Properties of interest
• Equilibrium structure
• Phonons
• Relaxation around defects
• Energy dispersion
• Density of states
• Spatial charge density
• Chemical bonding
• Magnetic interactions
• Dinamical simulations
• Phase boundaries

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Theory

• Stationary Shrodinger equation

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TheoryHartree-Fock method
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TheoryDensity functional theory
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Installation

• Installation size is 173Mb on CD
• WWW Sites
• http//www.chimifm.unito.it/teorica/crystal/crysta
  l.html
• http//www.cse.clrc.ac.uk/cmg/CRYSTAL/

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Installation

• CRYSTAL98 use
• Unix
• Linux systems(all versions)
• Windows NT

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Introduction

• The CRYSTAL package performs ab initio
  calculations of the ground state energy,
  elec-tronic wave function and properties of
  periodic systems. Hartree-Fock or Kohn-Sham
  Hamiltonians (that adopt an Exchange- Correlation
  potential following the postulates of
  Density-Functional theory) can be used. Systems
  periodic in 0 (molecules, 0D), 1(polymers, 1D), 2
  (slabs, 2D), and 3 dimensions (crystals, 3D) are
  treated on an equal footing. In each case the
  fundamental approximation made is the expansion
  of the single particle wave functions
  ('Crystalline Orbital', CO) as a linear
  combination of Bloch functions (BF) defined in
  terms of local functions (hereafter indicated as
  Atomic Orbitals, AOs).

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Structure

• The local functions are, in turn, linear
  combinations of Gaussian type functions (GTF)
  whose exponents and coefficients are defined by
  input. Functions of s, p(in the order 2z2-x2-y2
  xz yz x2-y2 xy) symmetry can be used. Also
  available are sp shells (s and p shells, sharing
  the same set of exponents).The use of sp shells
  can give rise to considerable savings in CPU
  time.

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Structure

• The program can automatically handle space
  symmetry 230 space groups, 80 layer groups, 99
  rod groups, 45 point groups are available
  (Appendix A). In the case of polymers it cannot
  treat helical structures (translation followed by
  a rotation around the periodic axis). However,
  when commensurate rotations are involved, a
  suitably large unit cell can be adopted.
• Point symmetries compatible with translation
  symmetry are provided for molecules. Input tools
  allow the generation of slabs (2D system) or
  clusters (0D system) from a 3D crystalline
  structure, the elastic distortion of the lattice,
  the creation of a supercell with a defect and a
  large variety of structure editing.

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Functionality

• The basic functionality of the code is outlined
  below.
• The single particle potential
• Restricted Hartree Fock Theory
• Unrestricted and Restricted Open Shell Hartree
  Fock Theory
• Density Functional Theory for Exchange and
  Correlation
• Effective Core Pseudopotentials

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Functionality

• Algorithms
• Parallel processing (replicated data)
• Traditional SCF
• Direct SCF

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Functionality

• Structural Editing
• Use of space, layer, rod and point group symmetry
• Removal, insertion deletion and substitution of
  atoms
• Displacement of atoms
• Rotation of groups of atoms
• Extraction of surface models from 3D crystal
  structure
• Cluster generation from 3D crystals
• Cluster of molecules from molecular crystals

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Functionality

• Properties
• Band structure
• Density of states
• Electronic charge density maps
• Electronic charge density on a 3D grid
• Mulliken population analysis
• Spherical harmonic atom and shell multipoles
• X-ray structure factors
• Electron momentum distributions
• Compton profiles
• Electrostatic potential, field and field
  gradients
• Spin polarised generalisation of properties
• Hyperfine electron-nuclear spin tensor
• A posteriori Density Functional correlation energy

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Wave function analysis and properties

• Total energy
• Hartree-Fock wave function
• Hartree-Fock wave-functionDF a posteriori
  correction for correlation
• DF SCF wave function
• Band structure
• Density of states
• Band projected DOSS
• AO projected DOSS
• All Electron Charge Density - Spin Density
• Density maps
• Mulliken population analysis
• Density analytical derivatives

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Wave function analysis and properties

• Atomic multipoles
• Electrostatic potential
• Electrostatic potential maps
• Point charge electrostatic potential maps
• Electric field
• Electric field gradient
• Structure factors
• Compton profiles
• Electron Momentum Density
• Fermi contact

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ADEQUATE DESCRIPTION OF COPPER BAND
STRUCTURE
Figure 3
Figure 4



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ADEQUATE DESCRIPTION OF MgO BAND
STRUCTURE
Figure 3
Figure 4



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The functionality of the various programs and
their links are as follows

• integrals
• definition of geometry and BS calculation of
  symmetry information classification, selection,
  computation of one-and two-electron integrals

scfdir definition of geometry and BS calculation
of symmetry information classification, selection
of one- and two-electron integrals computation of
one-electron integrals iterative solution of SCF
equation and calculation of two-electron integrals
fortran files geometry,BS, symmetry information
one- and two-electron integrals
scf iterative solution of SCF equations
ground state wave function
unformatted
formatted
properties ground state properties
convert conversion ascii/binary
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Compilation

• Crystal98 is written in FORTRAN 77 and is
  therefore easily compiled on architectures for
  which executibles are not provided. You may also
  wish to compile the code to alter the dimensions
  of internal arrays or to select compilation and
  linkage options to increase the performance of
  the code.

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Testing the Installation

• It is very important that the installation of the
  code is checked by running the validation suite
  which is contained on the CD

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The parallel Implementation

• CRISTAL98 supports parallel execution on modestly
  parallel hardware on computers (nodes) linked by
  relatively low perfomance networks (eg
  Ethenet).CPU and DISK resources are shared
  efficiently while the memory usage is replicated
  on each node.
• One node is chosen as the master.The master
  spawns the program onto other nodes (slaves) and
  operates dynamical load balancing of the task
  execution via a shared atomic counter.
• During integral generation a task is defined as
  the calculation of a block of integrals.Thus
  each node computes a number of integrals which
  are stored to its local disk.

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Basic problems of CRYSTAL98

• Optimization basis for concrete physical tasks
• Value Energy Fermi is either overestimated(DFT
  method) or underestimated(HF-method)
• Time of calculation depends from computer sizes
  memory (as HDD size, so Extended memory size)

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CRYSTAL 981.0February 26, 1999V.R Saunder,
R. Dovesi, C. Roetti, M. Causa, N.M. Harrison,
R. Orlando, C. M. Zicovish-Wilson

• http//www.chimifm.unito.it/teorica/crystal/crysta
  l.html
• http//www.cse.clrc.ac.uk/cmg/CRYSTAL/