![]() ![]() The SHIFT option or directive allows to modify the level shift in the RHF program, and EXPEC to calculate expectation values of one-electron operators (see section One-electron operators and expectation values (GEXPEC)). Other commands frequently used are START and ORBITAL (or SAVE) to modify the default records for starting and optimized orbitals, respectively. In open-shell cases, we recommend to use the WF, OCC, CLOSED, or OPEN cards to define the wavefunction uniquely. The default behaviour can be modified either by options on the command line, or by directives. In such cases, the OCC and/or CLOSED directives can be used to force convergence to the desired state. Normally, this works well in closed-shell and many open-shell cases, but sometimes wrong occupations are obtained. The Aufbau principle is used to determine the occupation numbers in each symmetry. By default, the number of electrons is equal to the nuclear charge, the spin multiplicity is 1 (singlet) for an even number of electrons and 2 (doublet) otherwise, and the wavefunction is assumed to be totally symmetric (symmetry 1) for singlet calculations. In contrast to older versions of molpro, the HF and RHF directives have identical functionality and can both be used for closed-shell or open-shell calculations. Also denoted 6-31G(d).UHF or UHF-SCF, options calls the spin-unrestricted Hartree-Fock program That a set of polarizing d-functions ( 6D) is included ![]() Maybe the most popular basis set in use today. Sets of polarization d-functions and one set of polarization f-functionsĪre added to heavy atoms, and the "2p" indicates that two sets of polarizationĪ polarized VDZ basis set from the Pople school. In addition to the 6-311G basis, the "+" indicates that diffuse s-Īnd p-functions are added to heavy atoms, the "3df" indicates that three Has been added to hydrogen also denoted 6-311G(d,p). The second asterisk indicates that a set of polarization p-functions Has been added to heavy atoms to supplement the 6-311G basis also denoted The asterisk indicates that a set of polarization d-functions ( 5D) Some workers consider this basis to be less flexible than Built like 6-31Gīut with a third layer of valence functions composed of a single, uncontracted Usually supplemented with polarization functions. (Recently-developedīasis sets don't include the "G" or its equivalent since they are essentiallyĪ popular VTZ basis set similar to the small 6-31G Stands for "Gaussian", indicating the type of primitive function. The "1" indicates that the outer valence basisįunctions are each built using a single uncontracted primitive. The "3" indicates that the inner valence basis functions are each built The "6" indicates that each core basis function is built using six primitives. Often used with a set of heavy-atom polarization functions (see 6-31G*). Includes the s-like combination (x 2 + y 2 + z 2).Ī VDZ basis set from the Pople school. Indicates that six (cartesian) functions are used in each d-set. Indicates that five functions are used in each d-set. Included to supplement the 3-21G basis, but only on second-row and heavierĪtoms (beyond neon). The asterisk indicates that a set of polarizing d-functions (6D) is Is adapted from one that was developed for a brief course within the PhysicalĪnd Chemical Properties Division at NIST ( 2). ![]() ![]() Some of the more common terminology is explainedĪn extensive list of acronyms has been published recently ( 1),Īnd a major reference work is currently in preparation. Theory and density functional theory, is cluttered with abbreviations,Īcronyms, and jargon. The literature of quantum chemistry, covering both molecular orbital Physical and Chemical Properties Division, National Institute of Standards Glossary of Common Terms and Abbreviations in Quantum Chemistry Thermochemistry: Prediction and Estimation of Molecular Thermodynamics" The following glossary is adapted from: K. ![]()
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