0000000000376914
AUTHOR
C. David Sherrill
Psi4: an open-source ab initio electronic structure program
The Psi4 program is a new approach to modern quantum chemistry, encompassing Hartree–Fock and density-functional theory to configuration interaction and coupled cluster. The program is written entirely in C++ and relies on a new infrastructure that has been designed to permit high-efficiency computations of both standard and emerging electronic structure methods on conventional and high-performance parallel computer architectures. Psi4 offers flexible user input built on the Python scripting language that enables both new and experienced users to make full use of the program's capabilities, and even to implement new functionality with moderate effort. To maximize its impact and usefulness, …
The à 1Au state and the T2 potential surface of acetylene: Implications for triplet perturbations in the fluorescence spectra of the à state
The cis–trans isomerization reaction on the T2 surface of acetylene and the lowest excited singlet state of acetylene, A 1Au, are investigated by ab initio electronic structure theory. We report optimized geometries, dipole moments, and harmonic vibrational frequencies of stationary points and adiabatic energy differences between them using basis sets as large as triple‐ζ plus double polarization with higher angular momentum functions, TZ(2df,2pd), and theoretical methods up to coupled‐cluster singles and doubles with a perturbative triples correction [CCSD(T)] and the equation‐of‐motion coupled‐cluster method (EOM‐CCSD). Our theoretical predictions should aid the interpretation of observat…