Element-label is a character string consisting of either the chemical symbol for the atom or its atomic number. The most-used Z-matrix format uses the following syntax:Įlement-label, atom 1, bond-length, atom 2, bond-angle, atom 3, dihedral-angle Īlthough these examples use commas to separate items within a line, any valid separator may be used. Using Internal CoordinatesĮach line of a Z-matrix gives the internal coordinates for one of the atoms within the molecule. These are set consistently for a maximum of 250,000 real atoms (including ghost but not dummy atoms), and a maximum of 250,000 Z-matrix centers (atoms, ghost atoms, and dummy atoms). There are restrictions on the size of a Z-matrix: the maximum number of variables and the maximum number of atoms within a calculation. Mole.irrep_name gives the associated irrep symbol (A1, B1 …).This section presents a brief overview of traditional Z-matrix descriptions of molecular systems. Irreducible representations ( Mole.irrep_id) and the symmetryĪdapted basis Mole.symm_orb. Symmetry which is initialized in the Mole object, including the IDs of Symm.label_orb_symm() needs the information of the point group To label the irreducible representation of given orbitals, ( irname, sum ( doccsym = ir ), sum ( soccsym = ir ))) > myocc ( mf ) Ag, double-occ = 3, single-occ = 0 B2g, double-occ = 0, single-occ = 1 B3g, double-occ = 0, single-occ = 1 B1u, double-occ = 2, single-occ = 0 B2u, double-occ = 1, single-occ = 0 B3u, double-occ = 1, single-occ = 0 print ( ' %s, double-occ = %d, single-occ = %d ' %. > import numpy > from pyscf import symm > def myocc ( mf ). They need to be added to the core Hamiltonian as shown in the examples However, SO-ECPs are not automatically applied to any methods in the current implementation. Spin-orbit (SO) ECP integrals can be evaluated using PySCF’s integral driver. Scalar type ECPs are available for all molecular and crystal methods.ĮCP parameters can be specified directly in input script using NWChem format.Įxamples of ECP input can be found in examples/gto/05-input_ecp.py. ECP ¶Įffective core potentials (ECPs) can be specified with the attribute Mole.ecp. The ordering of the basis functions can be verified with the method Mole.ao_labels(). The order of Cartesian GTOs is generated by the code below: For example, after applying all the rules above, we have the following The label z^2 for the Lz=0 component of d function as the short name ofģz^2 - r^2. Short notations are used for basis functions of s, p and d shells. Instead of the order`py`, pz, px used in the table above. The Wikipedia table of spherical harmonics ,Įxcept for the p functions for which the order of px, py, pz is used In each shell, the spherical parts of the GTO basis follow theĬondon-Shortley convention, with the ordering (and phase) given in Or just a single primitive Gaussian function that may have several angular components. On each atom, basisįunctions are grouped according to their angular momentum.įor each value of the angular momentum, the individual shellsĪre sorted from inner shells to outer shells, that is, from large exponents to small exponents.Ī shell can be a real atomic shell, formed as a linear combination of many Gaussians, Grouped in terms of the atoms they are assigned to. This means that basis functions are first Momentum, (3) shells, (4) spherical harmonics. Ordering of basis functions ¶ GTO basis functions are stored in the following order: (1) atoms, (2) angular A few basis for relativisticĬalculations (e.g. Types of spinors are assumed in the basis. \(l\) (corresponding to spinors with \(j=l-1/2\)) or 0. Kappa can have value \(-l-1\) (corresponding to spinors with \(j=l+1/2\)), The list ]] defines the angular momentum of theīasis, the kappa value, the Gaussian exponents and basis contraction coefficients. Time-dependent Hartree-Fock and density functional theory.Multi-reference perturbation theory (MRPT).Multi-configuration self-consistent field (MCSCF).Auxiliary second-order Green’s function perturbation theory (AGF2).Algebraic diagrammatic construction (ADC).Configuration interaction (CISD and FCI).Second-order Møller–Plesset perturbation theory (MP2).Molecular structure Molecular structure Contents.
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