Table 11.16 H2O MP2 harmonic frequencies (cm function of basis set (all electrons) " ) as a... |

Table 2. The Cauchy moments S(k) for Ne calculated at various levels of the CC hierarchy using the d-aug-cc-pV6Z basis-set (all electrons correlated). All numbers in a.u. |

Since these earlier papers, Laws et a/.575 have computed a large number of one-electron properties, using a near-HF wavefunction, and investigated their dependence on the basis set. All computed properties were within 5 % of experiment for the largest near-HF basis set. Pulay and Meyer576 have calculated the force constants of NHa with a variety of GTO basis sets, all of which yield excellent agreement with experiment. [Pg.151]

With a given basis set and electronic structure method, if all possible excitations (corresponding to physically meaningful transitions, or generated as artifacts from using an incomplete basis and an approximate functional) are included in the SOS for... [Pg.61]

An LCAO description of the electronic structure requires at least the minimal basis set (all orbitals that may be occupied in the ground state of the atom) of five d states per atom and the s state. Consideration of the bands from F ig. 20-1 indicates that in fact the highest-cnergy slates shown (for examples, H,s and X4) have p-like symmetry, and we shall not reproduce this with our minimal set, but the bands at this energy arc unoccupied in any case and it will be of little consequence. For constructing bands in solids, the angular forms for the d states in terms of cartesian coordinates, shown in Eq. (1-21), arc most convenient. Here we shall carry out the calculation explicitly for chromium, in the body-centered cubic structure it is carried out for the face-centered cubic structure in Problem... [Pg.479]

Table 24 The calculated rate constants for the electron-transfer reaction for three different systems in comparison with experimental values. The two different calculated values correspond to two different basis sets. All energies are from ref 82... [Pg.96]

Figure 1 shows the structure of all-trans-polymethineimine and Table 1 lists the optimized geometries for both HF and MBPT(2) methods with three basis sets, STO-3G, 6-31G, and 6-31G [68], We can see that both the size of the basis sets and electron correlation have a strong influence on the stable structure, especially on the difference between the two bond lengths, Tn=c and Yc-n-Table 2 presents the HF and MBPT (2) fundamental vibrational frequencies for all-trans-polymethineimine [68], The vibrational frequencies listed in each... [Pg.134]

Elxcept for the calculations made using the 3-21G basis set, all correlation energies were larger in magnitude for the syn -conformer, i.e. the electron correlation energy favours the syn -conformer for all basis sets besides 3-21G, where the correlation energy is very small, but favours the anti-conformer. [Pg.103]

The three-dimensional potential energy function was determined from the electronic energies of 150 selected conformations. Calculations were performed at the RHF/MP2 level with the 6-31lG(d,p) basis set. All the structures were fully optimized taking into account in some way the interactions with the remaining vibration modes. [Pg.161]

Table 11.9 Total energy (+76 au) as a function of basis set and electron correlation (all electrons)... |

A special Cl calculation, called full configuration interaction (FCI), is the most accurate, and most expensive, for a given basis set. All possible electron configurations are included. This is equivalent to complete-order coupled-cluster theory. For an A-electron molecule, the FCI result is attained when Ath excitations are included in the Cl or CC calculation. Unlike truncated Cl, such as CISD, FCI is size-consistent. Continuing the... [Pg.17]

Lastly, we mention the basis sets. All ab initio ECP computations after 1984 described in this chapter were done using valence Gaussian basis sets in conjugation with effective core potentials. Typically, valence Gaussian basis sets for the heavy metal are of (3s 3p 3d) quality where the numbers in front of s, p and d specify the numbers of contracted Gaussian functions. For lanthanides and actinides, obviously 4f-type Gaussian functions are included in the basis set. We will describe in individual sections the basis sets used prior-to describing the calculational results. We will also describe the valence space of electrons when ECPs are included. [Pg.49]

Karamanis, R, Maroulis, G., 8c Pouchan, C. (2006a). Basis set and electron correlation effects in all-electron ab initio calculations of the static dipole polarizability of small cadmium selenide clusters, (CdSe) , n = 1,2,3,4. Chemical Physics, 331(1), 19-25. [Pg.754]

The LMP2 and GVB-LMP2 methods can also be u.sed to study thermochemistry. As in all ab initio correlation methods which are applicable to molecules of reasonable size, it is not possible to converge the basis set and electron correlation sufficiently to achieve chemical accuracy without the use of... [Pg.2296]

electron integral evaluation step and the scaling of the two-electron integral transfonuation step. Of course, basis fiinctions that describe the essence of the states to be studied are essential (e.g. Rydberg or anion states require diffuse functions and strained rings require polarization fiinctions). [Pg.2189]

© 2019 chempedia.info