Materials and Process Simulation Center,
California Institute of Technology
Title of the Effort
Highly Parallelized Large Scale Atomistic Simulations
for Design of Materials
The objective is to develop theoretical methodologies
for practical computations of the structures and
properties of real materials that can be used in industrial process
design for manufacturing new materials.
William A. Goddard III, firstname.lastname@example.org
Department of Chemistry, Beckman Institute (139-74),
Caltech, Pasadena, CA 91125
Richard Friesner, email@example.com
Department of Chemistry, Columbia University, New York, NY 10027
Zhen-Gang Wang, firstname.lastname@example.org
Department of Chemical Engineering (210-41),
Caltech, Pasadena, CA 91125
Abhinandan Jain, email@example.com
Robotics, Jet Propulsion Laboratory (198-219),
Pasadena, CA 91109
Stephen Taylor, firstname.lastname@example.org
Department of Computer Science (256-80),
Caltech, Pasadena, CA 91125
The full 1994 report of the Materials and Molecular
Simulation Center in the Beckman Institute at Caltech is
also available on the World Wide Web (WWW).
includes the detailed progress reports on the NSF-GCAG project along with
projects supported by other agencies and by seven industrial
There is an enormous gap between current methodologies for
atomistic simulations and the level required for accurately describing
the relevant properties of industrially important materials. Our
strategy is to transcend from the most fundamental theory
(quantum mechanics, QM) to practical engineering designs in a sequence of
four or five levels as indicated in the following figure.
Figure 1. Hierarchy of Models for Simulation.
- Quantum Mechanics (QM)
First principles solution of the
Schrodinger equation (H F = E F) leads to accurate predictions of
properties (structures, chemical reactions, excited states); however, this
was limited to small systems (10 to 20 atoms) limiting the time and
distance scale to 1 ps and 1 nm.
- Force Fields (FF)
By averaging over the electrons from QM we
can obtain parameters (charges, force constants) while allowing
materials to be described in terms of atoms rather than
- Molecular Dynamics (MD)
Using force fields (FF) the
fundamental equations become Newton's
equations (F = MA) rather than the Schrodinger equations. This allows
practical calculations on 1000 to 5000 atoms rather than
10 to 20, extending the time and distance scale to 1 ns and 10
- Coarse Graining (CG)
By averaging over the atoms for MD, we
can obtain parameters representing groups of
atoms (molecules, segments), considerably simplifying the calculations.
- Statistical Mechanics (SM)
Using the CG description we can
examine materials in terms of the large scale motions relevant to
macroscopic experiments. This extends the time and distance scales to
1 microseconds and microns.
- Continuum Parameters (CP)
The results from SM are combined
to obtain macroscopic or continuum
parameters (free energies, phase diagrams, partition
coefficients, solubility parameters) suitable for
practical chemical engineering software (e.g., ASPEN-PLUS) for design of
Our team of 5 PI's has made significant progress on each of
the six tasks described under APPROACH. We have developed new theoretical
methods for quantum mechanics and molecular dynamics that scale
sufficiently slowly with size so as to be practical for the very large
systems of industrial interest. We are well along in parallelizing these
methods for optimal performance on highly parallel high performance
QM (PS-GVB) was combined with a
Poisson-Boltzmann treatment of solvant to obtain
self-consistent fully solvated wavefunctions. This was
tested on 29 molecules and found to give excellent results
(an accuracy of 0.03 electron volts).
the PS-GVB method
was extended to treat hyperpolarizability (for nonlinear
optical materials) and applied to the best
current organic materials with about 40
atoms. The results are excellent, indicating that theory can be used for
designing materials with improved properties.
A new generation of software (Gaussian dual space
density functional theory) has been developed for
predicting surface chemistry, thin film growth,
adhesion, corrosion, and other properties. It is being applied
to the CdTe and HgTe surfaces (in
collaboration with Hughes) and to corrosion inhibitors on iron oxide
(in collaboration with Chevron).
- Glass Temperature of Polymers.
A strategy has been developed
for using MD to predict glass temperatures of polymers. It has been
applied to eight polymers with excellent results.
This is being extended
to the study of copolymers and blends.
the new technology (CMM, RCMM) for
million atom MD simulations has been successfully
implemented on the KSR parallel supercomputer and is now in production
for studies of melting of nylons (with
Allied-Signal), diffusion of gases in polymers (Chevron),
surface tension (Chevron), and glass temperatures of polymers (Goodrich,
Chevron, Asahi Glass).
SIGNIFICANT EVENTS AND ACCOMPLISHMENTS
- PREDICTION OF GLASS TEMPERATURES OF POLYMERS.
A key, potentially very
significant industrial application for atomistic simulations is the
prediction of glass temperatures, T_g. Above T_g the polymer is soft and
be formed or extruded; below T_g it is stiff. Industry would like to
tune the glass temperature and the modulus to attain desired values by
alloying the polymer with different monomers (forming copolymers), by
cross linking, by blending or by using additives. Currently this is done
empirically leading to costly and wasteful experiments. If theory could
be used to predict the best choices there is the potential for
considerably reducing the number of such experiments.
Using the new MD techniques
developed under the GCAG and working with industrial collaborators
(Chevron, BF Goodrich, Asahi Glass), we have demonstrated (for eight cases)
excellent predictions of the glass temperature.
The simulations predict a glass temperature of 396K for teflon
in good agreement with the experimental value of 400K. Equally
exciting, analysis of the simulations explain the underlying phenomena
controlling the glass temperature. Namely it is the point above which
gauche-trans transformations compete with diffusion. Such concepts may
allow new applications for rapid
prediction of how the glass temperature is modified by changing the
material (carrying out large scale calculations only for selected cases).
- QUANTUM MECHANICS OF LARGE FINITE MOLECULES.
We have developed a new
methodology (PS-GVB) combining pseudospectral (PS) multi-grid and
dealiasing strategies with sophisticated many-body wavefunctions [e.g.,
generalized valence bond (GVB)]. PS-GVB has been extended to treat all
atoms of the periodic table. This combined a valence
bond formulation for estimating initial guesses of
wavefunctions, core effective potentials to treat the core electrons, and new
dealiasing functions. These methods scale with size as N^2 (rather
than the N^3 of standard programs) and are 10 to 100 times faster than
standard programs (depending on size). The PS-GVB method has been
extended to treat solvation effects
self-consistently using dielectric continuum methods, a Poisson-Boltzmann
solver, and a self-consistent reaction field method. Like DelPhi,
PS-GVB's Poisson-Boltzmann solver uses a cavity based on the real
molecular surface, rather than the spherical cavity used by other
programs. PS-GVB has been extended to calculate
hyperpolarizabilities and applied to the new high-beta NLO organics.
Second-order Moller-Plesset perturbation theory (MP2) has been
implemented into PS-GVB,
leading to improvements by a factor of 10 to 100,
depending on size of the system. Licenses of
this technology from Caltech and
Columbia to Schrodinger Inc. have been arranged. Schrodinger has added a
user-friendly interface and extended the program in many ways. On
October 15, 1994 the first full commercial release will be made. It is
anticipated that in two years PS-GVB will be in use at 100 US industrial
sites plus 100 US
- NONLINEAR OPTICAL MATERIALS.
We have developed a simple valence bond
theory (VB-CT) for predicting the trends in nonlinear optical properties
(hyperpolarization) of new organic materials as a function of donor,
acceptor, linker length, and solvent. VB-CT provides a way for
experimentalists to quickly select the proper combination to maximize the
various hyperpolarizabilities. This theory explains the derivative
relationship of various polarizabilities observed experimentally for
these materials. Using PS-GVB we have now succeeded in accurately
predicting the hyperpolarizabilities of the newest extremely high
hyperpolarizability materials, thus confirming both
the experiment and
the simple theory.
- QUANTUM MECHANICS OF CHEMICAL PROPERTIES ON SOLID SURFACES.
developed and tested a new methodology for predicting the chemical
properties at surfaces and interfaces which should be useful in
optimizing thin film growth. This methodology, GDS-DFT, extends density
functional theory to use of Gaussian type functions by using a dual space
strategy. This has been tested successfully on CdTe(100), HgTe(100),
GaAs(110), and is being used in two industrial
projects (HgCdTe with Hughes, corrosion inhibitors
Parallelize the solvate,
hyperpolarizability, and GVB-RCI methods.
Further develop and optimize the MP2, self-consistent GVB-RCI,
and GVB-RCI-MP2 methods. Apply to important industrial problems.
Vectorize and parallelize for the
CRAY T3D. Apply to important industrial problems.
Further develop and optimize. Test on the
prototype J-Machine. This should
allow up to 12 million atoms on the Intel-Paragon.
Extend to ring topologies and to infinite chains.
Parallize for KSR and Intel.
Extend grand canonical Monte Carlo for studying
phase transitions in diblock copolymers as a function of temperature
Schrodinger Inc., Pasadena CA (contact Dr. Murco Ringnalda, ph:
818-568-9392, fax: 818-568-9778, email: email@example.com)
has licensed the PS-GVB technology from Caltech and Columbia. They
have added a user-friendly interface, extensive user
guide, and extended the program in many ways. On October 15, 1994 the
first full commercial release will be made. It is anticipated that in
PS-GVB will be in use at 100 US industrial sites plus 100 US
Chevron Petroleum Technology Co., La Habra, CA (Dr. Yongchun Tang,
ph: 310-694-7550) uses PS-GVB, GDS-DFT, and MD-CMM to design new scale
inhibitors and corrosion inhibitors for oil
recovery applications (designing new and more effective calculations).
Allied-Signal, Morristown, NJ (Dr. Willis Hammond, ph:
201-455-4914) uses MD-CMM to predict structure and moduli of nylon polymers.
Hughes Research Labs., Malibu, CA (Dr. Jenna Zinck, ph:
310-317-5913) uses GDS-DFT to design metallorganics for MO-MBE deposition of
single crystal films.
DATE PROPOSAL: September 20, 1994
Last modified on September 26, 1995.
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