Computational Thermodynamics
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Computational thermodynamics is the use of computers to simulate
thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of ther ...
problems specific to materials science, particularly used in the construction of phase diagrams. Several open and commercial programs exist to perform these operations. The concept of the technique is minimization of
Gibbs free energy In thermodynamics, the Gibbs free energy (or Gibbs energy; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work that may be performed by a thermodynamically closed system at constant temperature and pr ...
of the system; the success of this method is due not only to properly measuring thermodynamic properties, such as those in the
list of thermodynamic properties In thermodynamics, a physical property is any property that is measurable, and whose value describes a state of a physical system. Thermodynamic properties are defined as characteristic features of a system, capable of specifying the system's stat ...
, but also due to the extrapolation of the properties of metastable
allotropes Allotropy or allotropism () is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: th ...
of the
chemical element A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
s.


History

The computational modeling of metal-based phase diagrams, which dates back to the beginning of the previous century mainly by
Johannes van Laar Johannes van Laar (10 July 1860 in The Hague – 9 December 1938 in Montreux) was a Dutch chemist who is best known for the equations regarding chemical activity ( Van Laar equation). Biography Van Laar lost his parents early, his mother in 1862 ...
and to the modeling of
regular solution In chemistry, a regular solution is a solution whose entropy of mixing is equal to that of an ideal solution with the same composition, but is non-ideal due to a nonzero enthalpy of mixing.P. Atkins and J. de Paula, ''Atkins' Physical Chemistry'' ( ...
s, has evolved in more recent years to the CALPHAD (CALculation of PHAse Diagrams). This has been pioneered by American
metallurgist Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...
Larry Kaufman since the 1970s.


Current state

Computational thermodynamics may be considered a part of
materials informatics Materials informatics is a field of study that applies the principles of informatics to materials science and engineering to improve the understanding, use, selection, development, and discovery of materials. This is an emerging field, with a goal ...
and is a cornerstone of the concepts behind the materials genome project. While crystallographic databases are used mainly as a reference source, thermodynamic databases represent one of the earliest examples of informatics, as these databases were integrated into thermochemical computations to map phase stability in binary and ternary
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s. Many concepts and software used in computational thermodynamics are credited to the SGTE Group, a
consortium A consortium (plural: consortia) is an association of two or more individuals, companies, organizations or governments (or any combination of these entities) with the objective of participating in a common activity or pooling their resources for ...
devoted to the development of thermodynamic databases; the open elements database is freely available based on the paper by Dinsdale. This so-called "unary" system proves to be a common basis for the development of binary and multiple systems and is used by both commercial and open software in this field. However, as stated in recent CALPHAD papers and meetings, such a Dinsdale/SGTE database will likely need to be corrected over time despite the utility in keeping a common base. In this case, most published assessments will likely have to be revised, similarly to rebuilding a house due to a severely broken foundation. This concept has also been depicted as an "inverted pyramid." Merely extending the current approach (limited to temperatures above room temperature) is a complex task. PyCalphad, a Python library, was designed to facilitate simple computational thermodynamics calculation using
open source code Open-source software (OSS) is Software, computer software that is released under a Open-source license, license in which the copyright holder grants users the rights to use, study, change, and Software distribution, distribute the software an ...
. In complex systems, computational methods such as CALPHAD are employed to model thermodynamic properties for each phase and simulate multicomponent phase behavior. The application of CALPHAD to high pressures in some important applications, which are not restricted to one side of materials science like the Fe-C system, confirms experimental results by using computational thermodynamic calculations of phase relations in the Fe–C system at high pressures. Other scientists even considered
viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...
and other physical parameters, which are beyond the domain of thermodynamics.


Future developments

There is still a gap between ab initio methods and operative computational thermodynamics databases. In the past, a simplified approach introduced by the early works of Larry Kaufman, based on Miedema's Model, was employed to check the correctness of even the simplest
binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...
systems. However, relating the two communities to
Solid State Physics Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the l ...
and Materials Science remains a challenge, as it has been for many years. Promising results from ab initio
quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...
molecular simulation packages like
VASP Viação Aérea São Paulo S/A (São Paulo Airways), better known as VASP, was an airline with its head office in the VASP Building on the grounds of São Paulo–Congonhas Airport in São Paulo, Brazil. It had main bases at São Paulo's two ...
are readily integrated in thermodynamic databases with approaches like Zentool.http://zengen.cnrs.fr/manual.pdf A relatively easy way to collect data for intermetallic compounds is now possible by using Open Quantum Materials Database.


See also

*
Phase diagram A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous ...
*
Gibbs energy In thermodynamics, the Gibbs free energy (or Gibbs energy; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work (physics), work that may be performed by a closed system, thermodynamically closed system a ...
*
Enthalpy of mixing In thermodynamics, the enthalpy of mixing (also heat of mixing and excess enthalpy) is the enthalpy liberated or absorbed from a substance upon mixing. When a substance or compound is combined with any other substance or compound, the enthalpy o ...
* Miedema's Model * Materials Genome *
UNIQUAC In statistical thermodynamics, UNIQUAC (a portmanteau of universal quasichemical) is an activity coefficient model used in description of phase equilibria. The model is a so-called lattice model and has been derived from a first order approxi ...
*
UNIFAC In statistical thermodynamics, the UNIFAC method ( UNIQUAC Functional-group Activity Coefficients)Aage Fredenslund, Russell L. Jones and John M. Prausnitz, "Group-Contribution Estimation of Activity Coefficients in Nonideal Liquid Mixtures", '' ...


References


External links

*
Official CALPHAD website
*
Python-based libraries for the calculation of phase diagrams and thermodynamic properties


* ttp://www.opencalphad.com/ Open Calphad
Thermocalc for Students

Pandat (free up to three components)

Matcalc (free up to three components, open databases available)



NIST

Thermodynamic Modeling using the Calphad Method
at
ETH Zurich (colloquially) , former_name = eidgenössische polytechnische Schule , image = ETHZ.JPG , image_size = , established = , type = Public , budget = CHF 1.896 billion (2021) , rector = Günther Dissertori , president = Joël Mesot , ac ...

MELTS Software for thermodynamic modeling of phase equilibria in magmatic systems

SGTE Scientific Group Thermodata Europe

Larry Kaufman at Hmolpedia
* * *{{cite journal , last1=Kirklin , first1=Scott , last2=Saal , first2=James E. , last3=Meredig , first3=Bryce , last4=Thompson , first4=Alex , last5=Doak , first5=Jeff W. , last6=Aykol , first6=Muratahan , last7=Rühl , first7=Stephan , last8=Wolverton , first8=Chris , title=The Open Quantum Materials Database (OQMD): assessing the accuracy of DFT formation energies , journal=NPJ Computational Materials , date=11 December 2015 , volume=1 , issue=1 , pages=15010 , doi=10.1038/npjcompumats.2015.10 , bibcode=2015npjCM...115010K , doi-access=free * pen Quantum Materials Database http://oqmd.org


University Courses on Computational Thermodynamics


Computational Thermodynamics for Materials Design KTH, Sweden MatSE580: Computational Thermodynamics of Materials, Pennsylvania State University, USAComputational Thermodynamics University of Brno, Czech Republic
Computational physics Materials science