BIOVIA MATERIALS STUDIO DFTB+DATASHEETBIOVIA Materials Studio DFTB+ is an improved implementationof the Density Functional based Tight Binding (DFTB) quantum
simulation method for the study of electronic properties ofmaterials. Combining near quantum mechanical accuracy
with solution speeds approaching those of classical atomistic
methods, BIOVIA Materials Studio DFTB+ offers uniquecapabilities to study and understand systems containing
hundreds of atoms. Problems that took more time or computepower than most researchers have available, such as defects
in semi-conductors, and interactions between organic andinorganic surfaces, are now practical to study using BIOVIA
Materials Studio DFTB+. These types of problems are common
throughout several industry sectors including catalysis,electronics, and chemicals.

WHAT DOES BIOVIA MATERIALSSTUDIO DFTB+ DO?
BIOVIA Materials Studio DFTB+ enables the optimization andstudy of dynamical properties of materials with quantum
mechanics accuracy but in significantly less time. Structures
can be optimized and molecular dynamics used to study
the temporal evolution of the structure. Properties such as
band structure, and atomic orbitals and Fermi surfaces canbe calculated and visualized, giving a deep understanding of
the electronic structure of materials. Population analysis andelectron density can be used to visualize charge distribution.
BIOVIA Materials Studio DFTB+ uses libraries of parameters
called Slater-Koster files to encapsulate the interactions
between the elements in the material. If the elements are
not parameterized, BIOVIA Materials Studio DFTB+ includes a
specific parameterization task to develop new parameter sets,
enabling extension to new systems.

KEY USES OF BIOVIA MATERIALS STUDIO DFTB+
Semiconductors
The ability to model systems containing thousands of atoms
enables researchers using semi-conductors to study the effectof defects on their systems.

Surface adsorbed monolayers
Capturing both the interactions at the surface between amonolayer and surface and the bulk of the monolayer requires
tools that can give an accurate electronic description but
still be applied to a large number of atoms. BIOVIA Materials
Studio DFTB+ satisfies both of these requirements, making
it applicable to a wide range of calculations where either
quantum mechanics approaches are too expensive, or forcefield
descriptions do not capture the level of detail.

Growth of structures on surfaces
Studying growth of inorganic crystals such as boron nitride on
diamond surfaces requires the ability to model bond formation
and breaking and do this on a large scale. BIOVIA Materials
Studio DFTB+ provides the accurate electronic structure
calculation and couples this with large system sizes, enabling
the study of realistic growth models.

THE MATERIALS STUDIO ADVANTAGEBIOVIA Materials Studio DFTB+ is operated from within theBIOVIA Materials Studio® environment. BIOVIA Materials Studio
provides an integrated user interface that is easy to use andquick to learn. BIOVIA Materials Studio Visualizer, the coreBIOVIA Materials Studio product, offers a wide range of modelbuilding and visualization tools that allow you to rapidly
construct models of the system of interest, perform BIOVIA
Materials Studio DFTB+ calculations, and analyse the results.
Integration in BIOVIA Materials Studio means that generating
new parameters is a single task which seamlessly utilizes
the BIOVIA Materials Studio DMol3 density functional theorymodule.
A flexible client-server architecture means that calculations
can be run on servers located elsewhere on your network.
Results are returned to your PC, where they may be displayed
and analyzed. You can easily produce high quality graphics ofstructures, including electron density maps. These structures,graphs, and other data such as video clips, produced fromBIOVIA Materials Studio DFTB+ output, can be instantly
exchanged with other PC applications.

DFTB is based on Density Functional Theory (DFT) but
uses empirical approximations to improve the performance
whilst maintaining accuracy. The main approximation in thetightbinding approach is the replacement of the exact manybody Hamiltonian in DFT with a parameterized Hamiltonianmatrix. In the DFTB description pseudo atomic wave functions,written in terms of Slater-type orbitals and spherical harmonics,
are used to model the electron density. The orbital basis isfitted to against DFT theory and then used to calculate theHamiltonian and overlap matrix elements. The DFTB approach
uses approximations to expand the total energy of the DFT
representation to the second order in charge density and spin
density fluctuations.
The matrix elements do not fully describe the total energy ofthe system, the remaining part of the total energy is included
as a short-range repulsive term which can be described in termsof pair wise potentials between atoms. The pair wise potentials
are acquired through a fitting process.
For systems where the balance of charges between pairs ofatoms is very small, BIOVIA Materials Studio DFTB+ also uses
self consistent charge (SCC-DFTB) to improve the descriptionof the bond. In order to simplify the calculations, the SCC
calculation is performed on Mulliken charges rather than thepotential and charge density.
Besides the usual electronic and short-range repulsive terms,
the final approximate Kohn-Sham energy additionally includes
a Coulomb interaction between charge fluctuations. At large
distances this accounts for long-range electrostatic forces
between two point charges and approximately includes
selfinteraction contributions of a given atom if the charges
are located at one and the same atom. Due to the SCC
extension, DFTB can be successfully applied to problems where
deficiencies in the non-SCC standard TB approach becomeobvious.

FEATURES AND CAPABILITIESCalculation tasks• Single point energies• Geometry optimization including options to optimize cell andperform rigid body optimization.
• Molecular dynamics using NVE, NVT, NPH and NPT
ensembles.
• Parameterization task for creating new Slater-Koster
parameter sets fitting to LDA/PWC, GGA/PW91 or GGA/PBE
functionals• All tasks work on non-periodic and periodic systems• Include van der Waals dispersion corrections• Restricted and un-restricted calculations• Accelerated SCF convergence by smearing Parameter Sets
• CH – parameters for hydrocarbons• CHNO – parameters for molecules containing carbon,hydrogen, nitrogen and oxygen• SiGeH – parameters for semi-conductors containing silicon,
germanium and hydrogen

Properties• Full density of states• Full band structure• Electron density visualization• Fermi surface visualization• Orbital energies and visualization• Population analysis
To learn more about BIOVIA Materials Studio, go toaccelrys.com/materials-studioOur 3DEXPERIENCE Platform powers our brand applications, serving 12 industries, and provides a richportfolio of industry solution experiences.
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HOW DOES BIOVIA MATERIALS STUDIODFTB+ WORK?