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Reduced Density Gradient Analysis


In all areas of chemistry, non-covalent interactions (NCI) are significant both within and between molecules. They have to do with the storage of genetic information, folding and unfolding of proteins, and molecular recognition. NCI analysis is also a powerful method for the analysis of non-covalent interactions. NCIs have been computationally characterized in recent years using substantial breakthroughs in computational methodologies, including wave function-based methods and methods derived from density flooding theory (DFT). Reduced density gradients (RDG) have recently been developed as a method to identify NCIs.

Our ServiceFig 1. Non-covalent interactions in organic-inorganic hybrid compounds derived from amino amides. (Avila-Montiel C, et al. 2020)

Alfa Chemistry offers its customers professional RDG analysis services to solve their research problems by taking into account all design factors such as requirements, cost, and delivery time. The RDG method has been widely used to visualize weak interaction regions and, in fact, it also has the ability to reveal chemical bonding regions.

RDG Function Method

Utilizing the density and its first derivative, the RDG is determined. Its a simple function of the electron density ρ(r) and its gradient to describe the deviation from a uniform electron distribution. The reduction gradient will have extremely large positive values in the region furthest from the molecule, where the density decays exponentially to zero. The reduction gradient has a very small value that is very close to zero in the region of covalent bonds and non-covalent interactions.

RDG Function Method

RDG is studying NCI through the electron density ρ(r) and its derived scalar and vector fields. This method shares a fundamental idea with DFT: since electron density and energy are closely correlated, it should be possible to examine interactions just from density. Interestingly, all contributions to the interaction energy, with the exception of the zero-level electrostatic force, could be connected to ρ(r). These approaches offer various benefits of natural explanation. Due to their three-dimensional character, they can be visually scrutinized, they are typically robust, and they are invariant with respect to the You-transformation of molecular orbitals.

Intrinsic reaction coordinate (IRC) for the dyotropic interconversion of D / L -1,2-diphenyl-1,2-dibromoethane, computed at the B3LYP/6-311g level with a continuum solvent correction for benzene.Fig 2. Non-covalent interactions in organic-inorganic hybrid compounds derived from amino amides. (Laplaza R, et al. 2020)

Our Service

Alfa Chemistry uses the Quantum ESPRESSO (QE) program for computational RDG calculations and NCI analysis. Quantum ESPRESSO is a very powerful first-principles calculation program with built-in RDG calculations.

Project NameReduced Density Gradient Analysis
DeliverablesWe provide all raw data and analysis services to our customers.
Samples RequirementOur services require specific requirements from you.
Timeline DecideAccording to customers' needs
PricePlease contact us for an inquiry

Application of RDG Function:

  • Analysis of new bonding situations: Tetrel bonds
  • Multiphase catalytic analysis: graphene sites
  • Analysis of interactions in biomolecules along molecular dynamics simulations

Our RDG calculation services significantly reduce costs, facilitate further experimentation, and accelerate the drug design process for our global customers. Our personalized, full-service approach will meet your innovative learning needs. If you are interested in our services, please feel free to contact us. We would be happy to work with you and see you succeed!


  • Avila-Montiel C, et al. (2020). "Non-Covalent Interactions in Organic-Inorganic Hybrid Compounds Derived from Amino Amides." Journal of Molecular Structure. 1202: 127258.
  • Laplaza R, et al. (2020). "NCIPLOT and The Analysis of Noncovalent Interactions Using The Reduced Density Gradient." WIR: Computational Molecular Science. 11(2): e1497.

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