## What Is Thermochemical Property

Thermochemistry, a branch of physical chemistry, studies the law of thermal effect in physical and chemical transformations. Specifically, chemical reactions may absorb or release energy, the same as phase change (melting, freezing, boiling, etc). It is helpful for understanding a given reaction, such as entropy changes, spontaneous or not, favorable or not. Endothermic reactions need to absorb heat, while exothermic reactions release heat. It combines the concept of thermodynamics with bonds energy. Thermochemical properties generally include enthalpy, entropy, Gibbs free energy, heat of combustion, heat of formation, *etc*.

Thermochemical properties prediction plays an important role in accurate predictions of chemical equilibrium, energy balances, thermodynamic properties of isomers. The acquisition of thermochemical data attracts more and more attention. Therefore, it is of great importance to use computational methods for the accurate prediction of thermochemical properties. Alfa Chemistry provides heat capacity calculation, enthalpy calculation, entropy calculation, Gibbs free energy calculation, calculation of heat of combustion, and calculation of heat of formation.

Figure 1. Thermochemical properties (Purnell, D.L.; Bozzelli, J.W. 2019)

## Applications of Thermochemical Properties

- Thermochemical properties can be applied to thermodynamic calculation, such as entropy calculation, thermodynamic potentials calculation, phase transitions calculation, and heat capacity calculation.
- Thermodynamic properties are important indicators applied by scientists and engineers to analyze specific areas of a physical system. They can be used in engineering design and safety engineering, including nanomaterials, engines, energy storage materials.
- Scientific researches of thermochemical properties involve not only chemical reactions but also physics (for example black-hole thermodynamics).

## Our Advantages

- Our thermochemical properties prediction services help to understand reactants' stability, the ease of reactions, and the function of materials by computational thermochemical parameters.
- We can can adequately characterize the materials by providing accurate thermochemical properties prediction, which helps to both save labor costs and time with high accuracy.

## Our Methods for Thermochemical Properties Prediction

Thermochemical properties prediction plays an essential role in fundamental issues of materials science. We are skilled at related theoretical methods, such as

### Ab initio methods

Ab initio-based calculations can be very accurate for predicting gas phase thermochemical properties and are usually more versatile than group contribution methods. We use an ab initio calculation method based on the theory of linear response activity density functional disorder to study the vibrational properties of molecules, and predict thermodynamic properties such as enthalpy and free energy. Our scientists apply various calculation methods such as G3MP2, the correlation consistent Composite Approach (ccCA) and so on to calculate the molar enthalpies of formation, model the energetics of molecules without empirically optimized parameters and predict energetics.

### Coupled cluster single-double and perturbative triple (CCSD(T)) methods

CCSD(T) method is used to calculate the diagnostic values for the structures. At the level of this method, it is possible to generate a wave function in a suitable form to execute a topological analysis of atoms in molecules. We focus on high-precision hybrid density functional methods and research, and support CCSD(T) calculation methods. Our perturbative explicitly correlated coupled-cluster method can perform accurate prediction of chemical reactivity including analyze reaction barrier heights, electronic reaction energies, atomization energies, and enthalpies of formation.

### Density functional theory methods

Density functional theory methods are suitable for high-throughput prediction of thermochemical properties rapidly and accurately. At Alfa Chemistry, density functional theory is used to optimize the geometry of the reactants, complexes, products and transition states involved in the reaction. Combined with the knowledge of tatistical mechanics, we use these important data to calculate thermodynamic properties. Moreover, we have built an empirical localized orbital correction model which improves the accuracy of density functional theory methods for the prediction of thermochemical properties for diverse molecules.

### First-principles phonon calculations

First-principles phonon calculations have been widely used in the analysis of mechanical properties, electronic structure, lattice vibration, *etc*. We address the thermochemical properties of selected molecules from first principles phonon calculations to investigate possible trends in their formation and common reduction agents, as well as their thermal stability.

### Hartree-Fock methods

At Alfa Chemistry, The geometric molecular structures we investigate are optimized iteratively, with each iteration using an increased level of theory to refine the solution toward the optimum. And the optimization operation is completed with the application of Hartree Fock methods. We also use Hartree-Fock methods to calculate vibration frequency, conformational energy, formation heat and proton affinity and offer accurate predictions of other thermochemical properties.

### Second-order Møller-Plesset perturbation theory

Second-order Møller-Plesset perturbation theory is the most economical wave function-based electronic structure method beyond the Hartree-Fock approximation that provides an approximate description of all relevant vdW interactions including electrostatics, induction, and dispersion. Our experts can use Møller-Plesset second-order perturbation theory and density functional theory to investigate multiple molecular interactions. Structural and energetic properties of various complexes are calculated using different calculation algorithms. The assessment of the above-mentioned methods is based on the comparison of the structures and interaction energies predicted by these methods with reference computational data.

### Customer Notice

### Customers provide

- Specific requirements of thermochemical properties prediction services
- Analysis cycle

### We deliver

- Calculation algorithms and methods
- Raw data
- Analysis results

Alfa Chemistry provides personalized and customized service of thermochemical properties prediction to satisfy our customers' innovative scientific study demands. Our thermochemical properties prediction assists in mastering important thermochemical parameters, promoting your scientific research and engineering project. Our clients have direct access to our staff and prompt feedback to their inquiries. If you are interested in our services, please contact us for more details.

Reference

- Purnell, D.L.; Bozzelli, J.W. Thermochemical properties: Enthalpy, entropy, and heat capacity of C2-C3 fluorinated aldehydes. Radicals and fluorocarbon group additivity.
*J. Phys. Chem. A*2019, 123(3): 650-665.