The wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude from which it is possible to calculate the likelihood of a potential result of a measurement made on the system. The most common symbol for the wave function is the Greek letter Ψ. In general, the wave function is a function of space and time, i.e., Ψ = Ψ(x, y, z, t). The wave function is the central element of quantum theory, which can completely describe a quantum system.

Fig 1. Simple energy diagram for molecular orbital wave functions of H2. (Muller R. P, et al. 2003)

Alfa Chemistry is dedicated to provide chemical researchers with a comprehensive and accurate wave function study service to solve some problems encountered in quantum mechanics research. Wave function analysis is of great importance for studying the electronic structure characteristics of chemical systems (e.g. bonding type and strength, charge distribution, electron delocalization), molecular properties (e.g. reactivity, electrical conductivity, evaporation enthalpy, solubility), and interactions with the external environment (e.g. weak intermolecular interactions, electron-excited leap modes).

### Our Service

To make it easier and better for researchers, Alfa Chemistry offers practical wave function studies in a competitive way. We have prepared the most convenient services for you. Our services cover calculations of natural bond orbitals (NBO), restrained electrostatic potentials (RESP), reduced density gradients (RDG), atoms in molecules (AIM), nuclear independent chemical shifts (NICS), *etc*. The following services are available to you.

#### Natural Bond Orbital Analysis

Alfa Chemistry uses the NBO program integrated in the Gaussian 09W package to provide NBO analysis, which has proven to be a useful tool to more easily interpret electronic structure calculations in a chemically meaningful way. The analysis relies solely on density matrices generated from calculations of the underlying electrical structure, and the NBO analysis involves converting non-orthogonal atomic orbitals to "natural" atomic orbitals, hybrid orbitals and bonded orbitals by sequentially converting complete and orthogonal sets.

#### Restrained Electrostatic Potential Calculation

Alfa Chemistry offers professional RESP calculations to meet their research needs. The RESP method is a well-respected and widely used simulation for assigning partial charges to molecules. We use the Multiwfn program for the calculation service. On the one hand it can be used to calculate RESP charges in their standard form, and on the other hand it can calculate electrostatic potential charges with custom charge constraints, atomic equivalence constraints and penalty function parameters for MK and CHELPG fits.

#### Reduced Density Gradient Analysis

Alfa Chemistry offers professional RDG analysis services. RDG has recently been developed as a method to identify non-covalent interactions (NCI). RDG method has been widely used to visualize weak interaction regions and, in fact, has the ability to reveal chemical bonding regions. We use the Quantum ESPRESSO program to calculate RDG calculations and NCI analysis.

#### Atoms-in-Molecules Analysis

AIM theory is a quantum chemical model that describes bonding in molecules based on the topological nature of the electron density scalar field. Alfa Chemistry uses the Multiwfn software package to provide professional AIM analysis services to perform all quantum mechanical calculations. The atomic and group properties predicted by AIM are consistent with the experimentally measured additive group contributions.

#### Nuclear Independent Chemical Shifts Calculation

As a computational tool for evaluating aromaticity, NICS is the most commonly used aromaticity index. Alfa Chemistry provides professional NICS calculation services using Gaussian program calculations to help them identify and quantify the aromaticity of compounds.

### Our Advantages

- Flexible and advanced computing methods
- Cost-effective and time-saving
- Personalized and customized innovative scientific research services

Our wavefunction study services significantly reduce costs, facilitate further experiments, and enhance the understanding of catalytic reactions for our customers worldwide. If you are interested in our services, please feel free to contact us. We are happy to work with you and witness your success!

Reference

- Muller R. P,
*et al*. (2003). "Valence Bond Theory."*Encyclopedia of Physical Science and Technology.*411-419.