Synopsis: Quantum chemistry made easier

A new method for computing electron properties in many-electron molecules yields better results at lower computational cost.
Synopsis figure

The quantum mechanical wave function in Schrödinger’s equation contains everything you need to know about a many-body system, but actually calculating properties such as the energies of electrons in a molecule can defeat even the most powerful supercomputers. For fifty years, researchers have known that such calculations should be possible using a different approach, one that involves the density matrix—a statistical description that avoids the need to use the full multielectron wave function. David Mazziotti of the University of Chicago now reports in Physical Review Letters his success at an improved density matrix calculation of the ground-state energies and other properties of several molecules, yielding better answers with much higher computational efficiency.

Since the late 1950s, theorists understood that ground-state molecular energies could be calculated with the use of a density-matrix approach that took electrons two at a time, and then summing over all electron pairs. The advantage is that a full N-electron calculation scales exponentially as N, whereas computing these properties with a two-electron density matrix would only scale polynomially with N. Such scaling means a huge payoff in the computational resources needed. But ensuring that these so-called reduced density matrices properly represent a full N electron system has been elusive.

Building on his own group’s recent work and that of Christian Kollmar at the Rijksuniversiteit Groningen, Mazziotti has developed a new form of the reduced density matrix that results in not only significant computational speedup, but also much higher accuracy in the results. The method permits better calculations of ground state energies, bond distances, and bond breaking for a range of molecules including HF, CO, and CH4, and should find wide application in computational chemistry. – David Voss


Announcements

More Announcements »

Subject Areas

Atomic and Molecular Physics

Previous Synopsis

Particles and Fields

New limits on dark matter

Read More »

Next Synopsis

Quantum Physics

Equality for quantum graphs

Read More »

Related Articles

Synopsis: A Crystal of Light and Atoms
Atomic and Molecular Physics

Synopsis: A Crystal of Light and Atoms

A predicted type of atom-light crystal could host phonon-like excitations, allowing for new ways to simulate the physics of solids.   Read More »

Viewpoint: An Arrested Implosion
Condensed Matter Physics

Viewpoint: An Arrested Implosion

The collapse of a trapped ultracold magnetic gas is arrested by quantum fluctuations, creating quantum droplets of superfluid atoms. Read More »

Synopsis: No Vacancy for Tunneling
Atomic and Molecular Physics

Synopsis: No Vacancy for Tunneling

The tunneling rate for cold atoms in an optical lattice can be made to depend on whether a neighboring site is occupied—a behavior that may reflect the tunneling in complex materials. Read More »

More Articles