Variational Monte Carlo on a Budget -- Fine-tuning pre-trained Neural
  Wavefunctions
Michael Scherbela Leon Gerard Philipp Grohs
Obtaining accurate solutions to the Schr\"odinger equation is the key
challenge in computational quantum chemistry. Deep-learning-based Variational
Monte Carlo (DL-VMC) has recently outperformed conventional approaches in terms
of accuracy, but only at large computational cost. Whereas in many domains
models are trained once and subsequently applied for inference, accurate DL-VMC
so far requires a full optimization for every new problem instance, consuming
thousands of GPUhs even for small molecules. We instead propose a DL-VMC model
which has been pre-trained using self-supervised wavefunction optimization on a
large and chemically diverse set of molecules. Applying this model to new
molecules without any optimization, yields wavefunctions and absolute energies
that outperform established methods such as CCSD(T)-2Z. To obtain accurate
relative energies, only few fine-tuning steps of this base model are required.
We accomplish this with a fully end-to-end machine-learned model, consisting of
an improved geometry embedding architecture and an existing SE(3)-equivariant
model to represent molecular orbitals. Combining this architecture with
continuous sampling of geometries, we improve zero-shot accuracy by two orders
of magnitude compared to the state of the art. We extensively evaluate the
accuracy, scalability and limitations of our base model on a wide variety of
test systems.