Electrostatic potential and field approximation for aluminosilicates in cation-substituted forms

Quick scheme for evaluation of atomic charges in arbitrary aluminophosphate sieves on the basis of electron densities calculated with DFT methods

“…Simultaneously, the estimation of the absolute EF values in the internal sieve space was achieved with a maximal deviation of 30%. 6,49 One should take into account that the RMS error between the approximate and calculated EP or EF values is smaller than the maximal deviations mentioned above. In the Mg-form of the philipsite aluminosilicate, the relative RMS error between the approximated and calculated EP or EF values was 20 and 16% only.…”

“…In the Mg-form of the philipsite aluminosilicate, the relative RMS error between the approximated and calculated EP or EF values was 20 and 16% only. 50 The analytical forms developed herein are computationally convenient and remain continuous within all the range of possible values of the variables. We can confirm this because of the large list of structures, including distorted ones, already considered by us in refs.…”

“…The charge dependences, combined with a CC technique, 4,5 allowed to achieve a quantitative EP picture with a maximal deviation of 30% on the basis of electron densities calculated using small AlPOs. 48 Our method, whose aim consists in the transfer of AMM approximations to any arbitrary system of the same chemical content but with different geometry, is based on accurate periodic calculations at a high level of theory for AlPOs possessing a ''small'' size elementary unit cell (UC) and relatively small number of AO per UC. The EP accuracy regarding the dependence of several AMMs on framework densities and by selecting a more appropriate training set of AlPOs for the approximation 6,49 was further improved up to 20%.…”

“…48 Our method, whose aim consists in the transfer of AMM approximations to any arbitrary system of the same chemical content but with different geometry, is based on accurate periodic calculations at a high level of theory for AlPOs possessing a ''small'' size elementary unit cell (UC) and relatively small number of AO per UC. The EP accuracy regarding the dependence of several AMMs on framework densities and by selecting a more appropriate training set of AlPOs for the approximation 6,49 was further improved up to 20%. Simultaneously, the estimation of the absolute EF values in the internal sieve space was achieved with a maximal deviation of 30%.…”

Point atomic multipole moments for simulation of electrostatic potential and field in all‐siliceous zeolites

“…[16][17][18] The advantage of this way is the universal character of the parameters obtained at the steps (b) and (c). As soon as the step (a) was done once, the parameters obtained at the steps (b) and (c) could serve for other systems of similar composition, if their characteristics are presented in the same terms (geometry and CC).…”