 |
| Born Brooklyn, New York, 1942. |
| Columbia University, B.S., 1963. |
| Harvard University, A.M., 1965; Ph.D., 1967. |
| University of Manchester, England, NATO Postdoctoral Fellow, 1967-68. |
| The University of Chicago, Professor, 1968-. |
| |
| Accolades |
| Fellow, American Academy of Arts and Sciences. |
| Fellow, American Physical Society. |
| 1976 Faraday Division of the Royal Chemical Society and the American Chemical Society Award in Pure Chemistry. |
| 1973 Marlow Medal. |
| 1972-1977 Camille and Henry Dreyfus Teacher-Scholar Fellow. |
| 1972-1973 Senior Visiting Fellowship, Cavendish Laboratory, Cambridge, England. |
| 1972-1973 Guggenheim Fellow. |
| 1969-1970 Dupont Faculty Fellow. |
| 1969-1971 Alfred P. Sloan Fellow. |
|
|
| Karl F. Freed |
| Professor |
|
|
| |
| Research Interests: |
| Our research include the statistical mechanics of polymers in the liquid phase, protein dynamics aggregation, and folding , equilibrium aggregation phenomena, and molecular electronic structure. |
| |
| We have developed a theory for the statistical
thermodynamics
of polymers in the liquid state. Our analytical theory is the first and
only one to describe the influence of monomer molecular structure on the
thermodynamic properties of polymer mixtures. Several applications explain
small angle neutron scattering and thermodynamic experiments for polymer
mixtures. Our theoretical predictions of a strong pressure dependence to
the small angle neutron scattering intensities has been verified. Likewise,
we have predicted the possibility that certain block copolymers will form
mesoscopically ordered self-assembled structures in the liquid phase upon
heating,a bold prediction subsequently verified experimentally.
Recent extensions of the theory consider random copolymers, the influence
of short chain branching, monomer structure and chain semiflexibility on
miscibilities of polymers in the liquid phase, as well as the phase behavior
of liquid crystalline systems and the glass transition in polymer systems.
The work on the glass transition is providing the first theoretical
understanding
for the molecular basis oof glass fragiliity. Other theoretical work on
polymers describes the common behavior exhibited by reversible equilibrium
aggregating systems, including synthetic polymers and the proteins actin
and tubulin. We have devised a density functional theory of interfaces
in polymer systems to describe interfaces between phase separated polymers
and surface segregation profiles of polymers near an impenetrable, patterned
surface. |
| |
| Flexible aqueous peptides and solution polymers have
important dynamical processes on time scales far exceeding current capabilities
for computer simulations. We have developed implicit solvent models that
enormously reduce the computer time for simulating protein dynamics while
reproducing the same dynamics as explicit solvent MD simulations for a
small penta-peptide and for the folding of the 36 residue villin headpiece.
This implicit solvent model has been used to study the folding dynamics
of small peptides and the aggregation of beta-amyloid core fragments. Recent
work compares the predictions of several widely used force fields for protein
simulations, showing that the dispersion in their predictions far exceeds
any errors in our implicit solvent model. The simulations show a residue
specific dependence of conformational transitions in individual amino acid
backbones. We have developed a mode-coupling theory for long time protein
and polymer dynamics that extends the information from computer simulations
to longer time scales. Our model for the unfolded state of proteins agrees
well with data from NMR and small angle scattering experiments and
simulatneously
explains the propenisites with which each amino acid participates in secondary
structures in folded proteins. |
| |
| We have developed a highly correlated ab initio electronic
structure method for the difficult problem of describing molecular electronic
excited states. The method is a multi-configurational generalization of
the widely used MPn single reference configuration methods that are available
in many electronic structure packages. These ab initio methods have been
applied to describe the excited states of a number of conjugated pi-electron
systems, where our computed energies and oscillator strengths rival in
accuracy the most advanced ab initio methods. Additional applications have
been made to computing two-dimensional methyl mercaptan and 3-dimensional
hydrogen sulfide potential energy surfaces for the electronic excited states
that participate in non-adiabatic photodissociation experiments carried
out by Professor Butler's group. (The computations have been performed
by a theory-experiment student also working with Prof. Butler.) Other work
is focused on computing electronic spectra of radicals in interstellar
space and the properties of biological chromophores in a protein
environment. |
| |
| Our unique electronic structure methods enabled us to
derive from first principles the true valence shell effective Hamiltonian
that is mimicked by the model Hamiltonians of purely semiempirical molecular
orbital theories of molecular electronic structure. We have computed the
first fully correlated "ab initio" pi-electron Hamiltonian that
demonstrates why some assumptions of semiempirical pi-electron theories
are correct, but our computations for small conjugated pi-electron systems
indicate deficiencies of these older methods along with theoretically justified
methods for their improvement. |
| |
| Selected References |
| Flory-Huggins Model of Equilibrium Polymerization and
Phase Separation in Stockmayer Fluid. Phys. Rev. Lett., 92,
045502 (2004). |
| Influence of Frequency Shifts on Electron Transfer
Processes.
J. Phys. Chem. B, 107 10341 (2003). |
| Investigations into Sequence and Conformational Dependence
of Backbone Entropy, Inter-Basin Dynamics and the Flory Isolated-Pair
Hypothesis
for Peptides. J. Mol. Bio., 331, 693 (2003). |
| Long time dynamics of Met-enkephalin: Test of mode-coupling
theory and implicit solvent models. J. Chem. Phys. 118, 5143-56
(2003). |
| The Polymerization of Actin: Thermodynamics near the
Polymerization Line. J. Chem. Phys, 119, 4070 (2003). |
| All-atom Fast Protein Folding: The Villin Headpiece.
Proteins, 49, 439 (2002). |
| New patterns of Polymer Blend Miscibility Associated
with Monomer Shape and Size Asymmetry. J. Chem. Phys. 116,
9983 (2002). |
| Theoretical Studies on Excited States of a Phenolate
Anion in the Environment of Photoactive Yellow Protein. J. Phys. Chem.
A 104, 2939 (2000). |
| Explanation for the Unusual Phase Behavior of
Polystyrene-b-Poly(n-alkyl
methacrylate) Diblock Copolymers: Specific Interactions. Macromolecules
33, 5292 (2000). |
| Lattice Cluster Theory for Pedestrians: The Incompressible
Limit and the Miscibility of Polyolefin Blends. Macromolecules
31,
6681 (1998). |
| More publications are available at http://home.uchicago.edu/~freed/ |
| |
|
Physical Chemistry 