Molecular Dynamics with RealQM

RealQM is an alternative version of textbook Standard Quantum Mechanics StdQM. RealQM is based on non-overlapping one-electron charge densities in 3d physical space which preserves fundamental principles of classical continuum mechanics of 

• casuality
• determinism
• locality
• separability. 

RealQM can be seen as the model Schrödinger was working towards after formulation his ground-breaking Schrödinger Equation SE capturing the spectrum of the H atom with one electron, as an extension to systems with many electrons. RealQM has shown to capture basic aspects of atoms and molecules.  

But history took another turn with a generalisation breaking with the above classical principles which became StdQM formulated in wave functions defined over $3N$ dimensional unphysical configuration space for a system with $N>1$ electrons. Schrödinger protested but was silenced by Bohr-Born-Heisenberg laying a foundation with is the same today. 

Let us consider the basic problem of formation of the H2 molecule from two neutral H atoms being drawn towards each other to find a stable configuration at a kernel distance of 1.4 atomic units under release of 0.17 Hartree as binding energy. 

RealQM models the dynamic formation of H2 by computing the forces acting on the kernels under Coulomb interaction between electrons and kernels and between kernel and kernel, and finding a balance at the distance 1.4 under release of 0.17 Hartree. The is a casual process driven by physical forces.

StdQM approaches the problem in a different way according to Born-Oppenheimer, by first locking kernel positions and then computing the corresponding electronic energy, which is added to a kernel-kernel potential and then differentiated with respect to kernel positions, followed by updating kernel positions in a process towards energy minimum. This is a non-casual process driven by non-physical forces.

The key difference is:

• RealQM: electron have local support and so build electronic potentials with physical forces.  
• StdQM: electrons have non-local support and so only build electronic energies without physical forces.

It thus appears that RealQM opens a new approach to Molecular Dynamics with possibly new capabilities in protein folding.