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Fitting the parameters in STO-LG In computational chemistry, the Slater-type orbital (STO) more accurately describes the qualitative features of the molecular orbitals than Gaussian functions (GF). However, calculating the two-electron integral using STO can be costly. On the other hand, integrating GFs is relatively cheap. One way to solve this problem is to use a linear combination of GFs to approximate a STO. Such linear combination of Gaussian functions is called contracted Gaussian functions (CGF)....

Calculating energy of 1D Schrödinger equation using Sympy I was reading Szabo’s book “Modern Quantum Chemistry” and saw the exercise questions that seem to be solvable via programming. Hence I decided to give it a try and pick up sympy at the same time. I was a mathematica user back in undergrad, but have not used it ever since. Maybe sympy will just do the same trick. Here is the question (exercise 1....

Speed comparison among numpy, cython, numba and tensorflow 2.0 Recently I have been working on speeding up some codes in pymatgen for finding the atomic neighbors within a cutoff radius. I was searching online and found that cython is a rather powerful tool for accelerating python loops, and decided to give it a try. A common comparison for cython is numba and I have heard many good things about it. A less common competitor is the recently released tensorflow 2....