For semi-empirical molecular orbital methods, the gradient of the potential energy can be calculated with negligiiIe additional computational expense. This allows powerful minimization methods to be used to ahdate the geometries of large molecules The particular minimization method used is shown to
A semi-empirical method for estimating molecular quadrupole polarizabilities
โ Scribed by Eric A. Gislason; Malini S. Rajan
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 374 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0009-2614
No coin nor oath required. For personal study only.
โฆ Synopsis
It IC demonstrated that a lo:+1c.g plot of (ticld-gradient) quadrupolc poldrizablhrlcs agm~s~ dqxAc pOi.lrizabllltle:b of "chern~celly smlthr" atoms can be well fit with n str.+t lint. The tiieorctical Justific2! tmn for thlb 1s dlscusscti. 'I Ile hypethesis is advanced that the average qundrupole polari~hility for a molecule can be estimated from the avcrdgc d~polc polnri-Lability using the be% tit to the atomic data This method works well for II 2. the only molecule with ;tn accurately known quadrupole polanzablhty.
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Calculations using the MNDO HE molecular\*rbital method predict that NHd, PH4 and H$3 are stable free radicals, and that local minima exist for H30 and H2Cl. The tendency of MNDO to overestimate the stability of such systems is traced to its neglect of overlap integrals. Results for Hz (both ground
A finite field method for calculating spherical tensor molecular polarizability tensors ฮฑ(lm;l'm') = โฮ(lm)/โฯ(l'm')\* by numerical derivatives of induced molecular multipole ฮ(lm) with respect to gradients of electrostatic potential ฯ(l'm')\* is described for arbitrary multipole ranks l and l'. Int