Density Functional Theory Calculations of the Structures, Binding Energies, and Infrared Spectra of Methanol Clusters

1998 ◽  
Vol 102 (1) ◽  
pp. 82-94 ◽  
Author(s):  
Fredrick C. Hagemeister ◽  
Christopher J. Gruenloh ◽  
Timothy S. Zwier
Author(s):  
Quintin Hill ◽  
Chris-Kriton Skylaris

While density functional theory (DFT) allows accurate quantum mechanical simulations from first principles in molecules and solids, commonly used exchange-correlation density functionals provide a very incomplete description of dispersion interactions. One way to include such interactions is to augment the DFT energy expression by damped London energy expressions. Several variants of this have been developed for this task, which we discuss and compare in this paper. We have implemented these schemes in the ONETEP program, which is capable of DFT calculations with computational cost that increases linearly with the number of atoms. We have optimized all the parameters involved in our implementation of the dispersion correction, with the aim of simulating biomolecular systems. Our tests show that in cases where dispersion interactions are important this approach produces binding energies and molecular structures of a quality comparable with high-level wavefunction-based approaches.


2018 ◽  
Vol 22 (09n10) ◽  
pp. 771-776 ◽  
Author(s):  
Xin Chen ◽  
Chiming Wang ◽  
Yuxiang Chen ◽  
Dongdong Qi ◽  
Jianzhuang Jiang

The infrared spectra of tetrakis(dibutylamino) phthalocyanine and octakis(dibutylamino) compounds were studied via theoretical investigations. The results reveal deep fusion of the peripheral alkylamino moieties with the phthalocyanine chromophore in the tetrakis(dibutylamino)- but not in the octakis(dibutylamino)-phthalocyanine compounds. The successive localized molecular orbitals (LMO) and bond order analyses give support for the infrared vibrational results.


2018 ◽  
Vol 32 (03) ◽  
pp. 1850024
Author(s):  
Rengi̇n Peköz ◽  
Şaki̇r Erkoç

The structural and electronic properties of neutral ternary PbxSbySez clusters (x + y + z = 2, 3) in their ground states have been explored by means of density functional theory calculations. The geometric structures and binding energies are systematically explored and for the most stable configurations of each cluster type vibrational frequencies, charges on atoms, energy difference between highest occupied and lowest unoccupied molecular orbitals, and the possible dissociations channels have been analyzed. Depending on being binary or ternary cluster and composition, the most energetic structures have singlet, doublet or triplet ground states, and trimers prefer to form isosceles, equilateral or scalene triangle structure.


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