Notes on quantum chemistry, teaching, and the occasional photograph.https://yhliang.com/https://yhliang.com/writing/dream-vault-i-climbing-down/https://yhliang.com/writing/dream-vault-i-climbing-down/Short story based on a memorable dream.Wed, 05 Aug 2026 00:00:00 GMThttps://yhliang.com/notes/periodic-systems/periodic-equation-of-state/https://yhliang.com/notes/periodic-systems/periodic-equation-of-state/Fitting diamond's energy-volume curve to the Birch-Murnaghan form, and what the quality of the HF reference does to MP2.Mon, 03 Jan 2022 00:00:00 GMThttps://yhliang.com/notes/periodic-systems/periodic-thermodynamic-limit/https://yhliang.com/notes/periodic-systems/periodic-thermodynamic-limit/Supercells and k-point sampling are the same limit approached two ways. Extrapolating diamond to infinite size, and why the Ewald correction matters.Sun, 02 Jan 2022 00:00:00 GMThttps://yhliang.com/notes/periodic-systems/periodic-density-fitting/https://yhliang.com/notes/periodic-systems/periodic-density-fitting/The four-index integral is too expensive for crystals. Density fitting, its four flavors in PySCF, and a first benchmark on diamond.Sat, 01 Jan 2022 00:00:00 GMThttps://yhliang.com/notes/quantum-mechanics/bras-kets-and-operators/https://yhliang.com/notes/quantum-mechanics/bras-kets-and-operators/The Dirac notation and the postulates of quantum mechanics.Mon, 18 Jan 2021 00:00:00 GMThttps://yhliang.com/notes/quantum-mechanics/variational-principle/https://yhliang.com/notes/quantum-mechanics/variational-principle/Notes on the variational principle, the workhorse behind approximate quantum chemistry.Mon, 16 Nov 2020 00:00:00 GMThttps://yhliang.com/notes/quantum-mechanics/angular-momentum-matrix-elements/https://yhliang.com/notes/quantum-mechanics/angular-momentum-matrix-elements/Building the matrix representation of angular momentum operators.Mon, 16 Nov 2020 00:00:00 GMThttps://yhliang.com/notes/quantum-mechanics/quantum-harmonic-oscillator/https://yhliang.com/notes/quantum-mechanics/quantum-harmonic-oscillator/Solving the quantum harmonic oscillator with the ladder-operator trick.Tue, 29 Sep 2020 00:00:00 GMThttps://yhliang.com/notes/quantum-mechanics/measurements-and-projection-operators/https://yhliang.com/notes/quantum-mechanics/measurements-and-projection-operators/What a measurement does to a quantum state, and the operators that describe it.Thu, 10 Sep 2020 00:00:00 GMThttps://yhliang.com/notes/quantum-mechanics/stern-gerlach-experiment/https://yhliang.com/notes/quantum-mechanics/stern-gerlach-experiment/An introduction to quantum mechanics through one of the most well known physical experiments.Sat, 01 Aug 2020 00:00:00 GMT