Debra Searles is the professional name for an Australian theoretical chemist whose married name is Debra Bernhardt. She is best known for her contributions towards understanding the Fluctuation Theorem

Fluctuation theorem

The fluctuation theorem , which originated from statistical mechanics, deals with the relative probability that the entropy of a system which is currently away from thermodynamic equilibrium will increase or decrease over a given amount of time...

. This theorem shows the Second law of thermodynamics

Second law of thermodynamics

The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...

 and the Zeroth law of thermodynamics

Zeroth law of thermodynamics

The zeroth law of thermodynamics is a generalization principle of thermal equilibrium among bodies, or thermodynamic systems, in contact.The zeroth law states that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.Systems are said to...

 can be derived mathematically rather than postulated as laws of Nature.

Personal Profile

Bernhardt is an Associate Professor in the Faculty of Science at Griffith University. Her PhD studies were in the field of quantum chemistry and her fields of research now include statistical mechanics, dynamical systems theory

Dynamical systems theory

Dynamical systems theory is an area of applied mathematics used to describe the behavior of complex dynamical systems, usually by employing differential equations or difference equations. When differential equations are employed, the theory is called continuous dynamical systems. When difference...

, nonequilibrium fluids and molecular dynamics simulations of fluids.

Research interests

Bernhardt's research interests are in the study of liquids under equilibrium and nonequilibrium conditions, development of the theory of nonequilibrium fluids and use of simulations to assist in understanding experimental results. Current research projects include:

Study of nonequilibrium liquids via statistical mechanics; nonequilibrium molecular dynamics; dynamical systems theory; chaos theory
The fluctuation theorem
The study of fluids in confined spaces
Development of algorithms for molecular dynamics simulations
Calculation of liquid properties: Combining molecular dynamics simulations with quantum mechanical calculations to determine properties of liquids

Selected publications

• D.J. Evans, D.J. Searles and E. Mittag (2001), "Fluctuation theorem
  Fluctuation theorem
  The fluctuation theorem , which originated from statistical mechanics, deals with the relative probability that the entropy of a system which is currently away from thermodynamic equilibrium will increase or decrease over a given amount of time...
  
   for Hamiltonian systems - Le Chatelier's principle
  Le Châtelier's principle
  In chemistry, Le Chatelier's principle, also called the Chatelier's principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently...
  
  ", Physical Review E, vol 63, 051105(4).
• H. Huber, B. Kirchner and D.J. Searles, (2002), "Is there an iceberg effect in the water/DMSO mixture?", Journal of Molecular Liquids, vol 98-99, 71-77.
• G.M. Wang, E.M. Sevick, E. Mittag, D.J. Searles and D.J. Evans, (2002) "Experimental demonstration of violations of the Second Law of Thermodynamics
  Second law of thermodynamics
  The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...
  
   , Physical Review Letters, vol 89, 050601.
• D.J. Searles and H. Huber, (2002), "Accurate determination of nuclear quadrupole coupling constants and other NMR parameters in liquids from the combination of molecular dynamics simulations and ab initio calculations" , Encyclopedia of Nuclear Magnetic Resonance: A Supplement, (John Wiley & Sons, Ltd, Section Ed T. Farrar), vol 9, 215-226.

See also

• Fluctuation theorem
  Fluctuation theorem
  The fluctuation theorem , which originated from statistical mechanics, deals with the relative probability that the entropy of a system which is currently away from thermodynamic equilibrium will increase or decrease over a given amount of time...
  
  
• Loschmidt's paradox
  Loschmidt's paradox
  Loschmidt's paradox, also known as the reversibility paradox, is the objection that it should not be possible to deduce an irreversible process from time-symmetric dynamics...
  
   - how can one reconcile thermodynamic irreversibility with the time reversibility inherent in the microscopic equations of motion for both classical and quantum mechanical systems
• Le Chatelier's principle
  Le Châtelier's principle
  In chemistry, Le Chatelier's principle, also called the Chatelier's principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently...
  
   - a nineteenth century principle that defied a mathematical proof until the advent of the Fluctuation Theorem.
• Crooks fluctuation theorem
  Crooks Fluctuation Theorem
  The Crooks equation is an equation in statistical mechanics that relatesthe work done on a system during a non-equilibrium transformation to thefree energy difference between the final and the initial state of the...
  
   - an example of transient fluctuation theorem relating the dissipated work in non equilibrium transformations to free energy differences.
• Jarzynski equality
  Jarzynski equality
  The Jarzynski equality is an equation in statistical mechanics that relates free energy differences between two equilibrium states and non-equilibrium processes...
  
   - another nonequilibrium equality closely related to the fluctuation theorem and to the second law of thermodynamics
• Green-Kubo relations
  Green-Kubo relations
  The Green–Kubo relations give the exact mathematical expression for transport coefficients in terms of integrals of time correlation functions.-Thermal and mechanical transport processes:...
  
   - there is a deep connection between the fluctuation theorem and the Green-Kubo relations for linear transport coefficients - like shear viscosity
  Viscosity
  Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
  
   or thermal conductivity
  Thermal conductivity
  In physics, thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction....
  
  
• Boltzmann
• Thermodynamics
  Thermodynamics
  Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
  
  
• Brownian motor
  Brownian motor
  Brownian motors are nano-scale or molecular devices by which thermally activated processes are controlled and used to generate directed motion in space and to do mechanical or electrical work...
  
  

External links

• Griffith Chemistry Debra Bernhardt
• Debra Searles (Bernhardt) http://chem.sci.gu.edu.au/staff/d_bernhardt_personal.html