Electron affinity (*E*ea) of an atom or molecule indicates the amount of energy released when an electron attached to a neutral gaseous atom or molecule forms a negative ion. Electron affinity reflects the ease with which an atom or molecule gains an electron. Ionization potential (ionization energy, *E*i) is the minimum amount of energy required to remove the most loosely bound electron of an isolated neutral gaseous atom or molecule, which is generally an endothermic process. Both electron affinity and ionization potential are fundamental molecular properties, and indicate important characteristics of molecules. Scientists use various calculations to compute these properties.

Figure 1. Electron affinity and ionization energy (Jha, R.; *et al*. 2021)

### Notable Factors

### Our Theoretical Methods

- Fock-space coupled cluster (FSCC) calculation

1. We use the FSCC method to learn the ground-state energy of an N-electron system and obtain the critical fractions of a system's excitation spectrum, including ionization potentials, electron affinities, and excitation energies corresponding to N-electron singlet and triplet states.

2. Our capabilities include the study of electronic spectra corresponding to the Pariser-Parr-Pople model with the full configuration-interaction results taken as the reference.

- Quantum electrodynamics coupled-cluster (QED-CC) calculation

1. We use the QED-CC model to investigate cavity-induced effects on the chemistry of molecules.

2. We also provide additional services to validate the accuracy of our models.

- Multi-configuration Dirac-Hartree-Fock (MCDHF) calculation

1. Our teams carry out the active space approximation calculations with the Breit interaction, the finite nuclear size effect, and quantum electrodynamic corrections.

2. We can deliver the report for electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions from the ground state.

3. We can offer the final calculated results, which have been compared to theoretical and experimental data, with high agreement achieved.

4. We can also predict new energy levels, oscillator strengths, line strengths, and transition probabilities, where no other experimental or theoretical results are available.

### Our Services

Our electron affinity and ionization potential predictions services require you to provide specific requirements and the timeline according to your needs. As soon as possible, we will provide you with raw data and analysis services.

**Alfa Chemistry can offer include but not limited to the following,**

**Molecular simulation**

Molecular simulation technology is widely used in various fields, making the structure of molecular atoms and other microscopic particles more specific and visual. We apply this method to reveal the relationship between structure and properties from a microscopic point of view. Our experts, therefore can predict the properties of various molecular structures, such as electron affinity and ionization potential.

**2D-QSAR**

The quantitative structure-activity relationship is a method of quantitatively studying the interaction between small organic molecules and biological macromolecules, including the absorption, distribution, metabolism, *etc*. And various physical and chemical properties or structural parameters of molecules are often used in this approach. We introduce the quantitative structure-activity relationship into the investigation of electronic structure and predict the electron affinity and ionization potential.

**Computation of HOMO/LUMO-level, EA, IP, redox potential, electrical conductivity**

We can calculate polymer ionization energy (Ip), electrical conductivity, redox potential, and electron affinity energy (Ea). We are also capable of analyzing frontier molecular orbitals (HOMO-LUMO) and chemical reaction pathways to study the charge transfer and predict electron affinity and ionization potential, helping us to understand redox reactions profoundly.

**QM/MM simulation**

The QM/MM simulation method can simulate biological processes by accurately modeling electrons embedded in protein structures or solvent environments. In this calculation process, we use the QM or MM approach to model the electronic sub-regions of interest and rapidly calculate the rest of the system. The algorithm we established by the QM/MM method can predict excitation energy, ionization energy, and affinity with electrons.

Vertical electron affinity is defined as the energy difference between negative ions and neutral molecules in insulating gases. A lower vertical electron affinity leads to a tendency to absorb electrons and a higher electron attachment ability. Scientists at Alfa Chemistry can help our clients calculate vertical EAs using various computational techniques.

The adiabatic electron affinity is given by the difference between the energy of the neutral system Li_{n} (in its most stable geometry) and the energy of the anionic cluster (also in its most stable conformation). The ability of adiabatic EA to be used as an adjunct potential for developing bioreductive anticancer drugs is its main significance. Scientists at Alfa Chemistry can help our customers calculate adiabatic EA. We mainly use the Density Universal Function Theory (DFT) method.

Alfa Chemistry provides fast, specialized, high-quality services of electron affinity and ionization potential predictions at competitive prices for global customers. Personalized and customized services of electron affinity and ionization potential predictions satisfy innovative scientific study demands. 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

- Jha, R.;
*et al.*Does confinement alter the ionization energy and electron affinity of atoms?.*Eur. Phys. J. D*2021, 75, 88.