SIESTA

Scinchez-Portal D, Ordejon P, Canadell E (2004) Computing the Properties of Materials from First Principles with SIESTA 113 103-170... 

One weakness of this treatment, however, is that it neglects entropic contributions. Entropic contributions were considered in the free energy profiles (FEP) calculated earlier using umbrella sampling [58] and Monte Carlo Free energy Perturbation [59], both using a QM/MM scheme and the AMI Hamiltonian for the QM part. Our group used the same SIESTA DFT-based QM/MM method described above... 

SIESTA 83 P. Ordejon, Institut de Ciencia de Materials de Barcelona, Barcelona, Spain... 

The mischief of civilisation is the intensive life, which demands intensive stimulation. Human nature requires pleasure. Wholesome pleasures require leisure. We must choose between intoxication and the siesta. There are no cocaine fiends in Log rune. 

Phys. Cond. Matter, 14, 2745 (2002). The SIESTA Method for Ab Initio Order-N Materials Simulation. 

Sometimes there are long, opinionated conversations, with everyone animated and taking part. Sometimes a silence falls among us that lasts for several hours once each of us is comfortable, watching the riverbank slide by or nodding on the edge of siesta. 

Since Violetta was out of town, I abandoned thoughts of a siesta after dinner and trotted up to the archive boxes in the attic to find the Mchiel file. It was thinner than a portrait painter in Constantinople, just a brief personal letter from Bernardo and the Maestro s even briefer response, dated the following week and written for him by my predecessor. I learned nothing I did not already know, such as that a nobleman writing on a topic that might interest the Council of Ten will do so in his own hand rather than trust a secretary. 

Figure 6.18. (Top) STM image of the flfe-plane of TTF-TCNQ taken at 63 K (Ft = 50 mV, /t = 1 nA). The image area is 5.3 nm x 5.3 nm. Reprinted with permission from Z. Z. Wang, J. C. Girard, C. Pasquier, D. Jerome and K. Bechgaard, Physical Review B, 67,121401 (2003). Copyright (2003) by the American Physical Society. (Bottom) Simulation of the STM image of the afe-plane of TTF-TCNQ, obtained with DFT calculations in the GGA performed with the Siesta code (Soler et al, 2002) using the Tersoff-Hamann approximation (see Section 4.2). The value of the charge density is 2 x 10 electrons/a.u., which is about 0.2 nm above the surface. Courtesy of Drs P. Ordejon and E. Canadell.

In this work we recalculate the structures of Au clusters with 6scalar relativistic Troullier-Martins pseudo-potentials , respectively, and within the SIESTA code" . In Fig 2 we present our results for the structures and relative binding energies. We see that GGA leads to planar structures whereas LDA favors 3D structures for n>7 clusters. Thus, in addition to relativistic effects, the observed planarity of Au clusters is accounted for using only the GGA level of theory. 

Sdnchez-Portal D, Ordejon P, Canadell E (2004) Computing the Properties of Materials from First Principles with SIESTA 113 103-170 Schaffer CE (2003) Axel Christian Klixbiill Jorgensen (1931-2001) 106 1-5 Schaffer CE, see Anthon C (2004) 107 207-301 Schenker S, see Hauser A (2003) 106 81-96... 

What nonsense Go home. This is siesta and you need to rest. ... 

One siesta time a week or two later, Violetta poked me and said, You asleep ... 

Webb WB, Dinges DF. Cultural perspectives on napping and the siesta. In Dinges DF, Broughton RJ, eds. Sleep and Alertness Chronobiological, Behavioral, and Medical Aspects of Napping. New York Raven Press, 1989 247-265. 

The relaxation of the structure in the KMC-DR method was done using an approach based on the density functional theory and linear combination of atomic orbitals implemented in the Siesta code [97]. The minimum basis set of localized numerical orbitals of Sankey type [98] was used for all atoms except silicon atoms near the interface, for which polarization functions were added to improve the description of the SiOx layer. The core electrons were replaced with norm-conserving Troullier-Martins pseudopotentials [99] (Zr atoms also include 4p electrons in the valence shell). Calculations were done in the local density approximation (LDA) of DFT. The grid in the real space for the calculation of matrix elements has an equivalent cutoff energy of 60 Ry. The standard diagonalization scheme with Pulay mixing was used to get a self-consistent solution. In the framework of the KMC-DR method, it is not necessary to perform an accurate optimization of the structure, since structure relaxation is performed many times. 

Computing the Properties of Materials from First Principles with SIESTA... 

Soler JM, Artacho E, Gale JD, Garcia A, Junquera J, Ordejon P, Sanchez-Portal D (2002) The SIESTA Method for ab initio Order-N Materials Simulation, J Phys Condens Matter 14 2745-2779... 

It was almost noon. I had hoped to call on Violetta, but I was lacking several hours sleep and might well have settled for a siesta instead. 

Although a spinel lattice has been used by most simulations to date, there is some evidence that cations may also occupy interstitial sites of the fee oxygen sublattice that are not used in the spinel structure. A structure with 40% cahons in non-spinel sites has been put forward by Paglia and coworkers [77]. Their work combined atomic potentials calculations to survey thousands of possible cation arrangements in both spinel and non-spinel locations. Then PW91 optimizations were carried out for selected structures with the localized basis set code SIESTA. 

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