Infrared spectra of inorganic aerosols: ab initio study of (NH4)2SO4, NH4NO3, and NaNO3

2014 ◽  
Vol 92 (3) ◽  
pp. 216-221 ◽  
Author(s):  
S. Bourahla ◽  
A. Ali Benamara ◽  
S. Kouadri Moustefai
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Basis Sets ◽  
Equilibrium Geometry ◽  
Mean Absolute Deviation ◽  
Gaussian Basis Sets ◽  
Absolute Deviation ◽  
Inorganic Aerosols ◽  
Crystal Code ◽  
High Level

The structures and vibrational spectra of inorganic aerosols, including ammonium sulfate (NH4)2SO4, ammonium nitrate NH4NO3, and sodium nitrate NaNO3 are investigated at the periodic ab initio quantum mechanical level with the CRYSTAL code, which is based on Gaussian basis sets. Local density (LDA), gradient-corrected (PW91), and hybrid (B3LYP) density functionals have been used and the results are compared with experiment. All three functionals reproduce the equilibrium geometry of these aerosols to a high level of accuracy. The calculations of the frequencies gave a mean absolute deviation from experiment of 3% for B3LYP, clearly showing that this functional performs extremely well in this case. The mean absolute deviation is about 7% and 6% for PW91 and LDA, respectively.

Evaluation of Gaussian basis sets in ab initio

1983 ◽  
Vol 111 ◽  
pp. 387-396 ◽  
Author(s):  
John W. Jost ◽  
Chester T. O'Konski
Keyword(s):  
Ab Initio ◽  
Basis Sets ◽  
Gaussian Basis Sets

Gaussian basis sets for ab initio calculation of NLO properties of polyatomic molecules

2010 ◽  
Vol 10 (3-6) ◽  
pp. 239-256
Author(s):  
Diego Paschoal ◽  
Marcello F. Costa ◽  
Georgia M.A. Junqueira ◽  
Hélio F. Dos Santos
Keyword(s):  
Ab Initio ◽  
Ab Initio Calculation ◽  
Polyatomic Molecules ◽  
Basis Sets ◽  
Gaussian Basis Sets ◽  
Nlo Properties

AB-INITIO MOLECULAR DYNAMICS IN THE FULL-POTENTIAL LMTO METHOD: DERIVATION OF A PRACTICAL FORCE THEOREM

1993 ◽  
Vol 07 (01n03) ◽  
pp. 262-265 ◽  
Author(s):  
M. METHFESSEL ◽  
M. VAN SCHILFGAARDE
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Local Density ◽  
Basis Set ◽  
Ab Initio Molecular Dynamics ◽  
Basis Sets ◽  
Full Potential ◽  
Major Advance ◽  
First Results ◽  
Lmto Method

A major advance in electronic structure calculations was the combination of local-density techniques with molecular dynamics by Car and Parrinello seven years ago. Unfortunately, application of the Car-Parrinello scheme has been limited essentially to sp materials because only in the plane-wave pseudopotential method forces are trivial to calculate. We present a systematic approach to derive force theorems with desired characteristics within complicated basis sets, which are applicable to all elements of the periodic table equally well. Application to the LMTO basis set yields an accurate force theorem, quite distinct from the Hellman-Feynman form, which is exceptionally insensitive to errors in the trial density. The forces were implemented in a new full-potential LMTO method which is suited to arbitrary geometries. First results for ab-initio molecular dynamics and simulated annealing runs are shown for some random small molecules and small clusters of silver atoms.

Uniform quality constrained gaussian basis sets

1977 ◽  
Vol 55 (7) ◽  
pp. 1181-1192 ◽  
Author(s):  
Paul G. Mezey ◽  
Imre G. Csizmadia
Keyword(s):  
Ab Initio ◽  
Optimization Technique ◽  
Quality Criterion ◽  
Basis Sets ◽  
Integration Time ◽  
Program System ◽  
Gaussian Basis Sets ◽  
Direct Optimization ◽  
Time Saving ◽  
Exponent Sets

Uniformly balanced (6S3P), (7S3P), and (8S4P) gaussian basis sets with identical exponent sets for functions describing the 2s and 2p subshells have been obtained for the first row atoms. The basis sets have been determined using a direct optimization technique; they are thoroughly balanced and satisfy a rigorous quality criterion. These uniform quality constrained basis sets were designed for applications in ab initio programs of the type of the GAUSSIAN 70 program system, that may utilize the integration-time saving constraint α2s = α2p.

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