Development and Implementation of Advanced Fitting Methods for the Calculation of Accurate Molecular Structures

Area of Science:

• Molecular modeling and computational chemistry.
• Quantum chemistry and physical properties of molecules.

Background:

• Accurate molecular structures are essential for understanding molecular properties, from electronic structure to dynamics.
• The semiexperimental approach, using moments of inertia from isotopologues, provides accurate results cost-effectively compared to high-level quantum methods.

Purpose of the Study:

• To present the Molecular Structure Refinement (MSR) software for determining equilibrium molecular structures.
• To detail the implementation and advanced features of the MSR software, including its graphical user interface.

Main Methods:

• Utilizing a semiexperimental approach based on nonlinear least-squares fitting of moments of inertia.
• Implementing advanced features such as automatic generation of internal coordinates (A1 symmetry) and the method of predicate observations.
• Validating the software with various test molecules and an application to glycine.

Main Results:

• The MSR software enables accurate equilibrium structure determination via the semiexperimental approach.
• Novel features like automatic internal coordinate generation and predicate observations enhance usability and accuracy.
• Successful determination of the semiexperimental structure for glycine's most stable conformer.

Conclusions:

• The MSR software provides a powerful, user-friendly tool for precise molecular structure determination.
• The semiexperimental method, enhanced by MSR's features, offers a viable alternative to computationally expensive quantum chemical methods.
• The successful application to glycine demonstrates the software's utility for complex molecular systems.