What’s new

@

Speed-up of ATK 2008.10 compared to 2008.02

System Speed-up Memory reduction

Azafulleroid (molecule, 97 atoms) 1.1 15%

6x6x6 MgO (bulk, 432 atoms, Gamma point) 3.5 38%

6x6x6 MgO (k-point sampling (2,1,1)) 2.3 32%

8x8x8 MgO (bulk, 1,024 atoms, Gamma point) 5.4 63%

AuSiAu (two-probe, 1,166 atoms*) 3.2 50%

The speed-up measures how many times faster the new version is compared to 2008.02 (a factor 2 means twice faster), while the memory reduction is given in percent (50% means half the memory).

* 782 atoms in scattering region, 1,166 in equivalent bulk

Speed-up and memory reduction for the two-probe system with 1166 Si and Au atoms. The two distinguishable regimes (breakpoint at 350 ks for the red curve) are the equivalent bulk run and the two-probe calculations, respectively.

Supercluster parallel scaling & speedup

Model: Au-Si nanowire-Au

CPU cores

Speedup

Total calculation time

0

20

40

60

80

100

120

140

160

4 8 16 32 64 128

CPU Cores

Cal

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time

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ATK 2008.02

ATK 2008.10

ATK 2008.10

New ATK

QuantumWise builds new platform

Old ATK

� Needed to restructure the old software,

to get solid foundation for growth

Development

Functionality

Time20102009 2011 20132012

New ATK

old ATK

Agile development, short development cycles

Releases

2008.10 : ”Old” ATK + VNL

2009.06 : ”New” VNL + ATK-SE

2010.01 : ATK-DFT alfaVNL-beta, ATK-SE update

Windows

2010.02 : Redhat

----------------------------------------------

2010.07 : ATK-DFT, VNL releaseATK-SE update, LDA+U

2010.12 : Improved accuracy

Features ATK 2008.10 versus 2010.02

�Electronic structure calculations» SIESTA-based method, plus inclusion of indirect atom pairs for improved accuracy

» Up to double-zeta double polarized (DZDP) numerical atomic orbital basis sets, with detailed user control of basis set parameters

» Norm-conserving (Troullier-Martins) pseudopotentials provided for all elements, with possibility to use customized pseudopotentials

» LDA-PZ, GGA-PBE GGA-revPBE exchange correlation potentials (also spin-polarized)

» Fermi level smearing for improved convergence stability

» Customizable Broyden/Pulay mixing for self-consistent scheme

» Monkhorst-Pack k-point sampling grids

�Calculation of» molecular spectra

» band structure of periodic structures

» Eigenfunctions (molecular orbitals, Bloch functions)

» Mulliken population analysis

» Real-space electron density and effective potential

» Forces (analytic Hellmann-Feynman)

�Ion dynamics» Quasi-Newton or steepest descent relaxation

» Constraints: fixed positions

» Nudged Elastic Band (NEB) transition state analysis

�Transport calculations» Two-probe systems NEGF using the TranSIESTA method (self-energy coupling to semi-infinite leads)

» Green's function description of non-equilibrium electron distribution in scattering region

» Finite bias

» Ability to treat heterogeneous systems through multi-grid solution to Poisson's equation

» Simulation of electrostatic gate

�Transport analysis» Transmission coefficients (k-point resolved) and transmission spectrum

» Spin-dependent current and conductance/resistance

» Transmission eigenvalues and real-space eigenchannels

» Surface density of states

» Real-space local density of states

» Fast evaluation of linear response current

» Collinear spin-torque transfer

» Molecular Projected Self-Consistent Hamiltonian eigenvalues and real-space eigenfunctions

�Work-flow control» Store and restore the state of a calculation for deferred analysis, restart, or initialization of a new calculation via the self-consistent density matrix

”New” ATK – new features

� Electrostatic gates, dielectric regions

� Simulation of charged systems + ambient dielectric constant

� Fast self-energy calculations, Krylov methods

� Double-contour integration, stabilize finite bias simulations (go to higher bias)

� New two-probe model; the to-date most consistent model

3-terminal device Single Electron Transistor

New algorithms (1)

Electrode self-energies, timings

H. H. Sørensen et al., PRB 79, 205322 (2009)

New algorithms (2)

D. E. Petersen et al., J. Comp. Phys. 227, 3174 (2007)

Green’s function calculation

NanoLanguage 2.0

� NanoLanguage 1.0 was introduced in 2006» Purpose: map ATK 2.0/TranSIESTA functionality into Python

� NanoLanguage 2.0 is the next step in the evolution» Goal (for the future): A unified object-oriented platform for all types of atomic-scale simulations

� Open and efficiency-enhancing» Many more query methods and user functions

» Simple, open storage classes

» GUI operations become user functions

» Unified file format (see next slide)

� Similar to ASE 2.0» Support for multiple “calculators” (ATK-SE, DFT, GPAW, …)

� And many other small and large improvements...!

File handling

� Unified file format

» All data stored in NetCDF files

» Open format (binary)

» User functions for storing and retrieving

data from files

» No more VNL files

� VNL interacts directly with file system

» File browser in GUI

ATK-DFT 2010.07 tentative plan

� Feature-complete compared to 2008.10

� Improved relaxations -------------�(already in 2010.02)

� NEB calculations

� Calculation of stress

� Improved convergence for two-probe systems, automatic detection of appropriate complex contour

� Improved analysis: PDOS, current density

� Improved parallel performance

� Parallelized memory

� Spin-polarized LSDA

� LDA+U

ATK-DFT features 2010.12

� GGA

� Ultrasoft pseudopotentials

� Optimized basis sets

� Correction for BasisSet superposition error

� (1-probe)

� (Non-colinear spin)

� (Finite-element grids)

ATK-SE 2010

� Same functionality as ATK-DFT, but with

semi-empirical model

� Force module for relaxations

� Slater-Koster models (tight binding)

New module: ATK-Classical

� Brenner potentials for C and H

� EMT potentials for metals

VNL 2010.01

• Bulk Builder

• Surface Builder

• Molecular Builder

• Database

• Scripter

• Job Manager

• 3D viewer (iso-surface, contour plotvolume plot)

• Atomic Manipulator (two-probe builder)

• (Display of bonds)

Comparison with VNL 2008.10

• Custom Builder

• Custom Analyzer

• Improved performance

• Improved workflow

• Support for several calculators

• More functionality in instruments

• (Two probe editor)

• (Support for easy input/output of external formats CIF, XYZ, old ATK, …)

• (Visualization of trajectories)

• ….

New Features

Features in () will be available in 2010.07

.com

Publication list

Full abstracts, links to article sourceSearchable (also in abstracts)>140 scientific articles published with ATK in 2008/2009>200 in total (since 2004)

quantumwise.com/forum

� User to user» General discussion forum

» Promote publications

» Share ideas, tips, scripts

� Users to QuantumWise» Feature requests

» Support channel

» Ask questions, search for answers

� QuantumWise to users» Announcements

» Tips & tricks

» New features delivered as scripts

Active since Dec 2008280 members

2700 posts 500 topics

40,000 views/months

Tutorials

New features delivered via the Forum

� Analysis extensions» Bulk DOS

» Projected DOS (PDOS)

» Symmetry reduction of k-point sampling for transmission & DOS

» Effective mass and band gap for semiconductors

» I–V curves

» Atomization energy

» Current density

� Geometry setup and manipulation» Graphene nanoribbons

» Nanotubes

» Relaxation under bias

� Plotting tools» K-point resolved transmission

» Band structure

» Voltage drop

� Miscellaneous» XYZ file manipulations

» Extracting data from VNL files

» Converting old ATK files to NanoLanguage