TURBOMOLE structure

Ahlrichs R, Bar M, Haser M, Horn H, Kolmel C (1989) Electronic structure calculations on workstation computers The program system turbomole. Chem Phys Lett 162 165-169... 

All of the systems were initially optimized using a much higher level of theory, in order to ensure that the OM2 method provides a realistic description of the structure. The method employed was the second-order Mpller-Plesset perturbation theory (MP2) [50] using the cc-pVDZ basis set [51]. The resolution-of-identity (RI) approximation for the evaluation of the electron-repulsion integrals implemented in Turbomole was utilized [52]. 

All electron calculations were carried out with the DFT program suite Turbomole (152,153). The clusters were treated as open-shell systems in the unrestricted Kohn-Sham framework. For the calculations we used the Becke-Perdew exchange-correlation functional dubbed BP86 (154,155) and the hybrid B3LYP functional (156,157). For BP86 we invoked the resolution-of-the-iden-tity (RI) approximation as implemented in Turbomole. For all atoms included in our models we employed Ahlrichs valence triple-C TZVP basis set with polarization functions on all atoms (158). If not noted otherwise, initial guess orbitals were obtained by extended Hiickel theory. Local spin analyses were performed with our local Turbomole version, where either Lowdin (131) or Mulliken (132) pseudo-projection operators were employed. Broken-symmetry determinants were obtained with our restrained optimization tool (136). Pictures of molecular structures were created with Pymol (159). 

TURBOMOLE, Program Package for ab initio Electronic Structure Calculations, User s manual, TURBOMOLE Version 5.8, 2005. 

Electronic Structure Calculations on Workstation Computers The Program System TURBOMOLE. 

Local density functional (LDF) quantum mechanical calculations for materials science. deMon for density functional calculations. Turbomole for Hartree-Fock and MP2 ab initio calculations. ZINDO for extended Fliickel, PPP, CNDO, and INDO semiempirical molecular orbital calculations and prediction of electronic spectra. Plane Wave for band structures of semiconductors. ESOCS for electronic structure of solids. Silicon Graphics and IBM workstation versions. 

Electronic Structure Calculations on Workstation Computers the Program System TURBOMOLE, R. Ahlrichs, M. Bar, M. Haser, H. Horn and Ch. Kalmel, Chem. Phys. Letters, 1989, 162, 165... 

Erisch MJ et al (2009) GAUSSIAN 09 (Revision A.02). Gaussian Inc, Wallingford Ahlrichs R, Bar M, Haser M, Horn H, Kolmel C (1989) Electronic structure calculations on workstation computers the program system TURBOMOLE. Chem Phys Lett 162 165-169 Ditto M, Brunner H, Lippitsch ME (1991) Picosecond spectroscopy of dihydro bdiverdin. Chem Phys Lett 185 61-64... 

The most common quantum chemical programs—Gaussian (8), GAMESS (9), Turbomole (10), CADPAC (11), ACES II (12), MOLPRO (13), MOLCAS (14), and the newly developed TITAN (15)—are able to run pseudopotential calculations. Please note that CADPAC and MOLCAS can only use so-called ab initio model potentials (AIMPs) in pseudopotential calculations. Such AIMP differ from ECPs in the way that the valence orbitals of the former retain the correct nodal structure, while the lowest-lying valence orbital of an ECP is a nodeless function. Experience has shown that AIMPs do not give better results than ECPs, although the latter do not have the correct nodal behavior of the valence orbitals... 

R. Ahlrichs, M. Bar, M. Haser, H. Horn, C. Koknel, Electronic structure calculations on workstation computers The program system Turbomole, Chem. Phys. Lett. 162 (1989) 165 M. Haser, R. Ahlrichs, Improvements on the direct SCF method, J. Comput. Chem. 10 (1989) 104 O. Treutler, R. Ahlrichs, J. Chem. Phys. 102 (1995) 346 R. Bauernschmitt, R. Ahlrichs, Treatment of Electronic Excitations within the Adiabatic Approximation of Time Dependent Density Functional Theory, Chem. Phys. Lett. 256 (1996) 454 S. Grimme, F. Furche, R. Ahlrichs, An improved method for density functional calculations of the frequency-dependent optical rotation, Chem. Phys. Lett. 361 (2002) 321 F. Furche,... 

Implementations of the spin-free DKH Hamiltonian exist by now for many standard quantum chemistry packages like Molecule-Sweden, Columbus, Turbomole, Molcas and Nwchem. The method has also been implemented in several programs for the calculation of periodic structures, in particular crystals (Boettger 1998b Fehrenbach and Schmidt 1997 Geipel and Hess 1997). 

Ahlrichs R et al. (2002) TURBOMOLE Program Package for ab initio electronic structure calculations version 5.5. Universitat Karlsruhe, Physical Chemist, Karlsruhe, Germany... 

The stnictures of the isomeric zwitterions 6a and 6b and five different structures of the anion 7 were studied by quantum-chemical methods. For this purpose, geometry optimizations at the SCF level with an optimized SVP basis set [23] were performed using the TURBOMOLE program system [24], Generally, the results of the computational studies were in good agreement with the experimentally established data. 

The ionization potentials and electron affinities of the H, C, N, O and F atoms have been computed by means of state-of-the-art electronic structure methods. The conventional coupled-cluster calculations were performed up to the connected pentuple excitation level. For the purpose of the basis set truncation correction the implementation of the CCSD(F12) model in Turbomole was applied. Final results were supplemented with relativistic and diagonal Born-Oppenheimer corrections. Estimated values of the IPs and EAs are in good agreement with the experimental values and the deviations do not exceed 0.7 meV, in the cases of H, C and N atoms and the IP of O atom. The results obtained for fluorine differ by ca. 1 and 5 meV from the experiment, respectively for the IP and EA. The EA of oxygen is plagued with discrepancy that amounts to ca. 4 meV. 

Time-dependent functional theory electronic structure calculations were performed with Gaussian 09 [35]. RI-CC2 calculations were performed with Turbomole [36]. Spectra were simulated with the Newton-X program [37, 38] interfaced to Gaussian 09. 

The efficiency of TURBOMOLE for the treatment of small to medium-size molecules carries over to laiger ca.ses. At first it was especially the exploitation of molecular symmetry which made a theoretical treatment of highly symmetric large molecules possible. The extreme //, symmetry has permitted SCF calculations for the fullerene C540 with an STO-3G basis, 2700 basis functions, by Scuseria. Thiel and co-workers treated C240 within the DFT approach employing an SV basis set with 2160 basis functions. In both studies it was concluded that the large hillerenes do not assume a spherical shape the preferred structure is a faceted equilibrium structure. 

Computational quantum chemistry has become an integral part of research in chemistry. TURBOMOLE can be applied to predict molecular properties such as structure parameters energetics, NMR chemical shifts or electronic excitations. Such calculations can be done routinely with a variety of methods on workstations or even on PCs for molecules with about 100 atoms in low symmetry and a few hundred atoms in high symmetry. This may require execution times of hours or even days on a single computer - but the calculations are feasible. Turn around times can be reduced on parallel computers, e.g., by a factor of 10 on a 12-node machine. 

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