Rajendra Maharjan

Education and Training

• PhD: Department of Chemistry, Oklahoma State University, Stillwater 74075, Oklahoma. [August 2017 - December 2023]
• MS : Central Deparment of Chemistry, Tribhuvan University, Kathmandu, Nepal.
• BS : Tri-Chandra Multiple Campus, Tribhuvan University, Kathmandu, Nepal.

Oklahoma State University

Project-1 : Assessing Order in Liquid, Supercooled, and Crystalline Water

This research focusses on studying water structural ordering in liquid, crystalline, and supercooled water, network topology analysis of water hydrogen bonded condensed system, dipole moment distribution of water in condensed phase.

• Developed an algorithm (nucleation_tracker written in both C++ and Python) to study network topology analysis and water structural ordering using an order parameter.
• Monitor closed rings distribution in liquid and supercooled water using different empirical potential water models at different temperatures.
• Studied intrinsic hydrogen bonded polygons in different known ice polymorphs and render the Pov‑Ray image unique to each ice polymorphs.
• Studied tetrahedral order parameter for water ordering in liquid, supercooled liquid, and ice.
• Stochastic growth of ice using crystal seed and direct coexistence method from pure water
• Network topology analysis and water structural ordering during molecular dynamics (MD) simulation.
• Study of crystal defects during ice formation.

Project-2 : Dipole Moment Distribution Analysis in Liquid Water and Ice

The dipole moment of gas phase water is accurately determined to be 1.85 D both experimentally and theoretically. However, the dipole moment of water in condensed phase is enhanced due to the environment effect through extensive hydrogen bonds. In this project, we mainly focus on various aspects of environmental effects to determine the dipole moment on target water molecule and study its moment distribution.

• Determine the dipole moment distribution of water in liquid and ice using quantum approach (QM) and ab‑initio molecular dynamics (AIMD).
• Studied the polarization effect from the environment on enhancing the dipole moment of gas phase water in condensed system.
• Developed an algorithm based on tabulated quantum calculation to determine the dipole moment of water at different temperatures that is comparable to pure QM calculations.
• Employed ice Ih and ice VII as a toy model to study moment distribution dependent on density, quality of hydrogen bonds, and hydrogen bond distance.

Project-3 : Water Ordering due to Hydrophobic Effect of Solvated Non-Polar Solute

Hydrophobic particles are better know for water ordering especially due to its tendency to form clathrate hydrates. Clathrate hydrates of water are mainly composed of pentagons and some other polygons like hexagons and quadrilaterals. We monitor the influence of water structural ordering on pure water in presence of non-polar solute particles. On the other hand, the salts may be classified as chaotropes or kosmotropes based on the nature of salt ions. We used our ring enumerator tool to determine the degree of water ordering in presence of salts.

• Studied how the hydrophobic particle enhance the water ordering using ’nucleation_tracker’ program
• Carefully monitor the constructive interference behavior of two hydrophobic particles on water ordering.
• Studied chaotropic effect of ions on water ordering.