Landmannalaugar and Thorsmork, Iceland.

Kamchatka, Kluchevskaya Sopka, Russia

the accuracy problem you described can be attributed to any known classical algorithm because of its heuristic nature. We cannot say in advance what error is before we run calculations. This is why I find some quantum algorithms such as QPE fascinating, we can put the error bar in advance.

An initio method is one which depends on the fundamental constants only such as charge of an electron, etc. The more non-fundamental constants (parameters) one introduces in a model the less it becomes ab initio and more empirical. This is why PBE is more empirical than any CC method.

Would love to join, thanks. Here is the link to my Google scholar profile:

scholar.google.com/citations?hl...