Dipole moment (μ) refers to the product of the distance between the centers of positive and negative charges and the quantity of charge carried by the centers. The mathematical expression of the dipole moment is μ=q×d. Dipole moment is a vector with a direction specified from the center of the positive charge to the center of the negative charge. The polarity of molecules can be expressed by dipole moment, which can determine the spatial configuration. Electric polarizability (α) is the relative tendency of a charge distribution to be distorted from its standard shape by an external electric field. The polarizability of an atom or molecule is defined as the ratio of its induced dipole moment to the local electric field.

Figure 1. Dipole moment (Kundu, A.; *et al*. 2020)

### Application

- Dipole moment is an essential physical quantity that can characterize the polarity of a molecule. It can be applied to investigate the interaction between polar molecules and a mutually soluble solution system that is formed between polar molecules.
- Dipole moment can be used to predict the relationship between the effective electric field and the macroscopic external field to further predict the polarization characteristics from the microstructure is obtained. This can provide useful information on the macroscopic properties of molecules.

### Our Features

- Dipole moment is calculated after molecular optimization of conformation with the lowest energy.

We apply various advanced simulation software such as Gaussian software, in which a higher level of theory is used to re-optimize the conformation of each compound with minimum energy to determine the dipole moment. Our teams can quantitatively measure the polarity of the molecule in this step.

- Multiple molecular functions for dipole moment calculation.

We support a diversity of calculation methods, including Hartree-Fock (HF), Moller-Plesset's second-order perturbation (MP2), and fourth-order perturbation (MP4 (SDQ)) without triple excitation, coupled clusters of single excitation and double excitation (CCSD) to obtain the wave function and energy of a molecule.

- Self-consistent field (SCF) method for polarization prediction.

Our teams introduce self-consistent field theories, which only depend on the electronic density matrices and are the simplest level of quantum chemical models, to specify the region for which you want the initial spin polarization to be flipped. We use SCF to distinguish between ferromagnetic and antiferromagnetic states. At Alfa Chemistry, both Hartree-Fock (HF) theory and Kohn-Sham (KS) density functional theory (DFT) are available in the SCF method. We can also calculate analytical energy gradients for all the self-consistent field wave functions.

- Dipole moment and polarizability predictions are closely related, and the corresponding configuration of the molecule can be calculated as well.

The electric dipole moment and polarizability are closely related to the structural features and electronic properties of clusters. We can therefore perform an unbiased structure search for low-lying energetic minima of clusters using the CALYPSO method combined with density functional theory calculations. The main candidates for the lowest energy neutral, cationic and anionic clusters are identified, and several new candidate structures for the cationic and anionic ground states are obtained.

### Our Services

Our dipole moment and polarizability 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,**

**QM/MM simulation**

In the QM/MM simulation process, each atom bond is given to a dipole moment in the force field, and the electrostatic interaction can be described through dipole-dipole interaction. Our teams perform a QM/MM molecular dynamics simulation for the target molecule at room temperature, and we calculate the dipole moment and take the mean value. We can study the relative energies, dipole moment values, and the structural properties of solvent effect (water, methanol, and ethanol).

A pair of isomerism molecules often have different conformations, and each of them owns different energy. In the equilibrium state, the proportions of various conformations are different. We perform both structural isomers calculation and stereoisomers calculation methods to measure the dipole moment and predict polarizability with our various search algorithms and calculation approaches

**Van der Waals interaction simulation**

In general, the van der Waals potential increases with the increase of dipole moment, polarizability, and the ground state vibrational energy of electrons. We characterize different molecules by calculating dipole moment or polarizability and comparing the van der Waals forces using the data obtained.

**UV-Vis spectrum prediction**

Our teams calculate the entire UV-Vis spectrum of the system using the dipole moment of the ground state and the transition dipole moment between the excited states. We provide reliable analysis to explain why this system has an ultraviolet absorption peak of certain intensity based on the transition dipole moment density and the decomposition of the transition dipole moment to the molecular orbital transition.

Alfa Chemistry provides fast, specialized, high-quality services for dipole moment and polarizability predictions at competitive prices for global customers. Personalized and customized services of dipole moment and polarizability 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

- Kundu, A.;
*et al*. Dipole moment propels π-stacking of heterodimers of fluorophenylacetylenes.*J. Phys. Chem. A*2020, 124(37), 7470-7477.