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Recent developments in ADF


Title: Recent developments in ADF Author: G te Velde Last modified by: Mauro Stener Created Date: 10/18/2001 6:35:07 PM Document presentation format – PowerPoint PPT presentation

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Title: Recent developments in ADF

ADF2007.01 The universal density functional
package for chemists Prof. Mauro Stener (Trieste
  • General intro DFT
  • ADF overview
  • Application areas
  • Technical features
  • Recent developments ADF
  • New functionality

Hierarchy of Computational Methods
  • Ab initio quantum chemistry (MP2, CC, CI)
  • Max. 10 atoms, systematic improvements, accurate
    if HF is good starting point!
  • Density functional theory (DFT)
  • Typically 100 atoms, accurate if Exc reliable
  • Handles difficult systems without problems
  • QM/MM
  • Typically 10,000 atoms
  • DFT accuracy at active site, environment effects
  • MM or MD (force fields)
  • Fast, but inaccurate, no bond-breaking etc.

Walter Kohn
Density Functional Theory (DFT)
  • Nobel prize Walter Kohn 1998 in chemistry(!)
  • Electron density ? is basic quantity
  • Exchange and correlation effects included through
    approximate Exc ? (meta-) GGAs, hybrid
  • Successful applications
  • equilibrium geometries, binding energies
  • molecular properties accessible IR, NMR, ESR,
    UV/Vis, CD, .

DFT the Kohn-Sham (KS) equations
  • ADF solves the KS equations for molecules

Orbital energies
KS Hamiltonian
Molecular orbitals
DFT the Kohn-Sham (KS) equations
Exchange-correlation energy functional APPROXIMATE
D! Must be properly chosen!
Electron density
DFT the Kohn-Sham (KS) equations
  • In ADF molecular orbitals are expanded according
    to LCAO
  • A basis set must be chosen

Basis functions must be properly chosen!
ADF developers
  • Baerends group, Amsterdam (1973 now)
  • Ziegler group, Calgary (1978 - now)
  • Many other academic groups
  • SCM
  • Spin-off Baerends group
  • Coordinate developments
  • User developer support
  • GUI development
  • Implement what users want ..

Evert-Jan Baerends
Tom Ziegler
Application areas for ADF
  • Whole periodic table
  • Types of systems
  • Molecules in gas phase (ADF)
  • Solvated molecules (e.g. COSMO)
  • Active site in proteins (QM/MM)
  • Polymers, slabs surfaces, solids (BAND)
  • Applications in chemistry materials science
  • Popular application areas
  • heavy element and transition metal compounds
  • homogeneous and heterogeneous catalysis
  • spectroscopy, molecular properties
  • Chemical analysis energy decomposition, fragment

Accuracy of ADF
  • Accurate, tunable numerical integration scheme1
  • No pseudopotential or ECP approximations needed
  • Stable SCF convergence for transition metal
  • Modern exchange-correlation functionals
  • Slater Type basis sets

1 G. te Velde and E. J. Baerends, J. Comput.
Phys. 99 (1), 84 (1992)
Basis Sets in ADF Slater Orbitals
  • Benefits of Slater type basis sets
  • nuclear cusp and correct asymptotic behavior
  • fewer Slaters than Gaussians needed
  • BAND numerical orbitals and Slaters
  • ADF has basis sets for every situation
  • Whole periodic table Z 1 - 118
  • frozen core and all-electron
  • Relativistic and non-relativistic (ZORA)
  • SZ, DZ, DZP, TZP, TZ2P, QZ4P (basis set limit)
  • Even-tempered, diffuse

ADF numerical techniques
  1. LCAO formulation (STO basis set)
  2. Numerical integrals
  3. Density fitting

Improved Slater type basis sets
E. van Lenthe and E.J. Baerends Journal of
Computational Chemistry 24 (2003) 1142
Modern meta-GGA and hybrid Exc functionals
Approx. 50 Exc functionals evaluated in single
Analysis with ADF
  • Fragment analysis
  • Bond energy decomposition
  • Electrostatic interaction
  • Pauli (exchange) repulsion
  • Orbital interactions
  • Advanced charge density analyses Voronoy,
    Hirshfeld, Nalewajski bond orders
  • Use of full molecular symmetry
  • Third-party analysis software NBO

1 Bickelhaupt Baerends, Rev. Comput. Chem.
2000, 15, 1.
ADF speed
  • Linear scaling techniques used
  • Density fitting (atom-pair based)
  • Efficient in parallel
  • Symmetry

C. Fonseca Guerra, J.G. Snijders, G. te Velde,
E.J. Baerends Theor. Chem. Acc. 99 (1998) 391
Functionality of ADF
  • Energetics, Potential Energy Surfaces
  • Single point, geometry optimization, transition
    state search, analytic frequencies,
  • Tracing of reaction path (IRC)
  • Computation of any electronic configuration
  • Spectroscopic properties
  • NMR, EFG, EPR, Raman, IR, hyperfine interactions,
    UV/Vis, CD, ORD, VCD, core properties
  • Bond energy analysis
  • Periodic structures treated with comparable
    method (BAND)

Model Hamiltonian options
  • State-of-the-art xc functionals
  • potential LDA, GGA, GRAC1, SAOP2, hybrids
  • energy LDA, GGA, meta-GGA, and hybrid energy
  • Spin restricted or unrestricted
  • Relativistic effects
  • scalar approximation ZORA (superior to Pauli)
  • spin-orbit (double-group symmetry)
  • Environment
  • Solvent COSMO, QM/MM, DRF, Frozen density
  • Protein QM/MM

1 Schipper et al., J.Chem. Phys. 112 (2000)
1344-1356 2 Grüning et al. J.Chem. Phys. 114
(2001) 652-660
Spectroscopic properties
  • Fast Raman intensities
  • Spin-orbit effects in Time-dependent DFT
  • Vibrational Circular Dichroism

Potential Energy Surface - improvements
  • MO6 class of xc energy functionals implemented
  • SCF convergence trouble-shooting (2006 2007)
  • Hybrid functionals during SCF (2006)
  • Analytic frequencies at GGA level (2006)
  • Improved Optimizer (2007)
  • Transition state search improvements (2007)
  • Frequency scan also after analytical frequencies
    (2007) to remove doubt on imaginary frequencies
  • Spin-orbit gradients (2007) geometry
    optimization, TS, numerical frequencies

SCF convergence trouble-shooting
  • Typical problematic systems for SCF convergence
  • Many close-lying energy levels around HOMO and
  • Certain lanthanides with open-shell f-electrons
  • Molecules with multiple transition metals, metal
  • New methods (ADF2006)
  • Electron smearing with stepwise reduction of
    smearing parameter
  • Averill-Painter method with gradual change in
    (fractional) occupations
  • ADF2007 NEWDIIS improved DIIS implementation?

ADF2006 Hybrid functionals during SCF
  • Uses energetic fit (Prof. Handy et al.) with
    additional efficiency refinements
  • Provides
  • orbitals
  • orbital energies
  • (some) molecular properties ESR with hybrids
  • Gradients with hybrids not yet available

E. van Lenthe, unpublished
2006 Analytic frequencies at GGA level
  • Important for IR spectra and classification
    stationary point on PES (minima, TS)
  • Frequency calculations time-consuming
  • ADF2006 analytical implementation (CPKS)
  • Four times faster than numerical frequencies
  • Timing example
  • 105 atoms, DZ basis, accint 3
  • 128 Itanium2 1.6 GHz cores
  • 2.7 hours wall-clock time

S. K. Wolff, Int. J. Quantum Chem., 2005, 104 645
ADF scaling on SGI hardware
Large frequency calculation scales up to 128
cores Best scaling with Itanium2, quad-core and
dual-core Xeons also OK Recently scaling improved
further (development version)
Improved geometry optimizer
  • Strong coordinates, 30 organic molecules
  • Optimizer Average steps to
  • ADF2006 7.4
  • ADF2007-cart 7.3
  • ADF2007-delocal 6.1
  • Weak coordinates, 18 weakly bound systems
  • ADF2006 41.5
  • ADF2007-cart 15.5
  • ADF2007-delocal 9.8
  • Improvements largest for strict convergence
    criteria, weakly bound, and floppy systems

Swart, Bickelhaupt, Int. J. Quant. Chem. 2006,
106, 2536
Technical Parallel Windows HP-MPI
  • Parallel Windows version
  • Impressive speed on quad-core
  • Limited speed-up from 2 to 4 due to memory
  • HP-MPI message passing library
  • Supports many interconnects
  • no recompilation needed
  • included in ADF distribution
  • performance improvement

Some non-confidential future plans ..
  • 3D-RISM, solvent model (Gusarov, Kovalenko,
  • DFTB (DF Tight-Binding), fast DFT-based
    semi-empirical method
  • Magnetic Circular Dichroism property
  • Hybrid TDDFT NBO analysis properties
  • Python scripting, combine with other codes /
  • Meta-GGAs in BAND
  • Speed-ups large ADF jobs and NMR calculations

Thank you for your attention! Questions now?
Free 30-day trial available at Questio
ns outside presentation to
ADF2006 Spin-orbit splitting in excitations
Double-group symmetry used Shows split up in
UV/Vis spectra due to spin-orbit
coupling Important for optical spectra of heavy
F. Wang, T. Ziegler, E. van Lenthe, S.J.A. van
Gisbergen, and E.J. Baerends, Journal of
Chemical Physics, 2005 122 p. 204103183. F.
Wang, and T. Ziegler, the Journal of Chemical
Physics, 2005 123 p. 194102
Transition State search improvements
  • Nudged Elastic Band
  • HCN example in ADF now converges in 9 steps (was
  • End points optimized at same time (minimizations)
  • Partial Hessian
  • Improves (semi-empirical) Hessian guess, e.g.
    molecule on metal surface
  • Difference between convergence and
  • Still considerable speed-up for less critical

Environment effects (2) Frozen-density embedding,
subsystem DFT
  • DFT in DFT, QM/QM
  • One active site, multiple frozen sites
  • Efficient for large systems
  • Solvent effects on spectroscopic properties
  • Original implementation by Wesolowski
  • More recent work in ADF by Jacob, Neugebauer,