Forces and atomic relaxations in the pSIC approach with ultrasoft pseudopotentials

We present the scheme that allows for efficient calculations of forces in the framework of pseudopotential self-interaction corrected (pSIC) formulation of the density functional theory. The scheme works with norm conserving and also with ultrasoft pseudopotentials and has been implemented in the plane-wave basis code {\sc quantum espresso}. We have performed tests of the internal consistency of the derived expressions for forces considering ZnO and CeO$_2$ crystals. Further, we have performed calculations of equilibrium geometry for LaTiO$_3$, YTiO$_3$, and LaMnO$_3$ perovskites and also for Re and Mn pairs in silicon. Comparison with standard DFT and DFT+U approaches shows that in the cases where spurious self-interaction matters, the pSIC approach predicts different geometry, very often closer to the experimental data.Comment: 11 pages, 2 figure

Effect of graphene substrate on the spectroscopic properties of photovoltaic molecules: role of the in-plane and out-of-plane π-bonds

La estructura electrónica del pentaceno decorado con grupos dipolos (d-pentaceno) y adsorbido en un sustrato de grafeno se ha estudiado dentro de la teoría de la densidad funcional. Se han considerado tres configuraciones de referencia, a saber, la molécula ideal sin distorsiones, la molécula real, incluidas las distorsiones intramoleculares y la molécula adsorbida en el grafeno. Los cálculos muestran una redistribución de carga notable dentro del sistema d-pentaceno + grafeno debido a la distorsión molecular, así como a la formación de enlaces π débiles entre la molécula y el sustrato. Además, el efecto de la modificación química de la saturación terminal con –H por –OH y = O se verifica para explorar la posibilidad de “ingeniería de niveles”. La parte imaginaria de la función dieléctrica del d-pentaceno en las conformaciones ideal y distorsionada y la molécula adsorbida en el grafeno se calcularon dentro de la aproximación de la fase aleatoria. Los resultados muestran que, aunque las distorsiones moleculares cambian apreciablemente el espectro de absorción del d-pentaceno aislado, la molécula adsorbida exhibe un espectro óptico que imita bastante al grafeno único.The electronic structure of pentacene decorated with dipole groups (d-pentacene) and adsorbed onto a graphene substrate has been studied within the density functional theory. Three reference configurations have been considered, namely the ideal molecule without distortions, the actual molecule including intramolecular distortions and the molecule adsorbed onto graphene. Calculations show a noticeable charge redistribution within the d-pentacene + graphene system due to molecular distortion, as well as the formation of weak π-bonds between the molecule and the substrate. Additionally, the effect of the chemical modification of the terminal saturation with –H by –OH and =O is checked to explore the possibility of “levels engineering”. The imaginary part of the dielectric function of d-pentacene in the ideal and distorted conformations and the molecule adsorbed at graphene were calculated within the random phase approximation. Results show that, even though molecular distortions change apreciably the absorption spectrum of isolated d-pentacene, the adsorbed molecule exhibits an optical spectrum which mimics quite much that of single graphene.• National Science Centre of Poland: Proyectos 2013/11/B/ST3/04041 and DEC-2012/07/B/ST3/03412 • Junta de Extremadura: Ayuda GR15105peerReviewe

Effect of graphene substrate on the spectroscopic properties of photovoltaic molecules: role of the in-plane and out-of-plane π-bonds

La estructura electrónica del pentaceno decorado con grupos dipolos (d-pentaceno) y adsorbido en un sustrato de grafeno se ha estudiado dentro de la teoría de la densidad funcional. Se han considerado tres configuraciones de referencia, a saber, la molécula ideal sin distorsiones, la molécula real, incluidas las distorsiones intramoleculares y la molécula adsorbida en el grafeno. Los cálculos muestran una redistribución de carga notable dentro del sistema d-pentaceno + grafeno debido a la distorsión molecular, así como a la formación de enlaces π débiles entre la molécula y el sustrato. Además, el efecto de la modificación química de la saturación terminal con –H por –OH y = O se verifica para explorar la posibilidad de “ingeniería de niveles”. La parte imaginaria de la función dieléctrica del d-pentaceno en las conformaciones ideal y distorsionada y la molécula adsorbida en el grafeno se calcularon dentro de la aproximación de la fase aleatoria. Los resultados muestran que, aunque las distorsiones moleculares cambian apreciablemente el espectro de absorción del d-pentaceno aislado, la molécula adsorbida exhibe un espectro óptico que imita bastante al grafeno único.The electronic structure of pentacene decorated with dipole groups (d-pentacene) and adsorbed onto a graphene substrate has been studied within the density functional theory. Three reference configurations have been considered, namely the ideal molecule without distortions, the actual molecule including intramolecular distortions and the molecule adsorbed onto graphene. Calculations show a noticeable charge redistribution within the d-pentacene + graphene system due to molecular distortion, as well as the formation of weak π-bonds between the molecule and the substrate. Additionally, the effect of the chemical modification of the terminal saturation with –H by –OH and =O is checked to explore the possibility of “levels engineering”. The imaginary part of the dielectric function of d-pentacene in the ideal and distorted conformations and the molecule adsorbed at graphene were calculated within the random phase approximation. Results show that, even though molecular distortions change apreciably the absorption spectrum of isolated d-pentacene, the adsorbed molecule exhibits an optical spectrum which mimics quite much that of single graphene.• National Science Centre of Poland: Proyectos 2013/11/B/ST3/04041 and DEC-2012/07/B/ST3/03412 • Junta de Extremadura: Ayuda GR15105peerReviewe

The influence of physical rehabilitation on arterial compliance in patients after myocardial infarction

Background: The aim of this study was to determine the effect of 6-week physical training on the mechanical properties of the arteries, in patients (pts) after acute myocardial infarction (MI). Methods: The group under investigation consisted 119 pts after their first acute MI qualified for the second stage of post-hospital training. Only 64 pts (Group 1) underwent the training program. The remaining 55 pts (Group 2) could not participate in it. All the pts underwent an initial exercise test, an ultrasound cardiac scan and a pulse wave velocity (PWV) measurement by means of the COMPLIOR system. Group 1 underwent cardiac rehabilitation program according to Model A or B, depending on exercise tolerance at baseline. Then, both groups had another exercise test and another PWV measurement. Additional PWV measurements were taken in both groups after 6 months. Results: Both groups were comparable with respect to demographic data, the site of MI, the method of treatment, left ventricular function, mean exercise time, the workload attained and mean PWV values at baseline (12.8 ± 1.6 m/s vs. 12.2 ± 2.7 m/s). In group 1 a significant increase in exercise capacity was observed: from 6.46 ± 2.7 to 8.95 ± 2.16 MET, and the PWV values were significantly lowered from 12.8 ± 1.6 to 8.7 ± 1.8 m/s. Group 2 showed only a slight lowering of PWV from 12.2 ± 2.7 to 10.8 ± 2.3 m/s. Conclusions: Controlled physical training after MI significantly improves systemic arterial compliance, probably through improving the endothelial function. (Cardiol J 2007; 14: 366-371

Effect of electron correlations in Pd, Ni, and Co monowires

We investigated the effect of mean-field electron correlations on the band electronic structure of Co, Ni, and Pd ultra-thin monatomic nanowires, at the breaking point, by means of density-functional calculations in the self-interaction corrected LDA approach (LDA+SIC) and alternatively by the LDA+$U$ scheme. We find that adding static electron correlations increases the magnetic moment in Pd monowires, but has negligible effect on the magnetic moment in Co and Ni. Furthermore, the number of $d$-dominated conductance channels decreases somewhat compared to the LDA value, but the number of $s$-dominated channels is unaffected, and remains equal to one per spin.Comment: to appear in PR

Different origin of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

The mechanism for the ferromagnetic order of (Ga,Mn)As and (Ga,Mn)N is extensively studied over a vast range of Mn concentrations. We calculate the electronic structures of these materials using density functional theory in both the local spin density approximation and the LDA+U scheme, that we have now implemented in the code SIESTA. For (Ga,Mn)As, the LDA+U approach leads to a hole mediated picture of the ferromagnetism, with an exchange constant $N\beta$ =~ -2.8 eV. This is smaller than that obtained with LSDA, which overestimates the exchange coupling between Mn ions and the As $p$ holes. In contrast, the ferromagnetism in wurtzite (Ga,Mn)N is caused by the double-exchange mechanism, since a hole of strong $d$ character is found at the Fermi level in both the LSDA and the LDA+U approaches. In this case the coupling between the Mn ions decays rapidly with the Mn-Mn separation. This suggests a two phases picture of the ferromagnetic order in (Ga,Mn)N, with a robust ferromagnetic phase at large Mn concentration coexisting with a diluted weak ferromagnetic phase.Comment: 12 pages, 11 figure

Protein and sugar content of tubers in potato plants treated with biostimulants

The use of biostimulants and cultivar selection play an important role in modern potato farming because they influence tuber yield and quality. The nutritional value and processing suitability of potato tubers are affected by their content of total protein, reducing sugars and sucrose. The aim of this study was to determine the effect of biostimulants on the content of total protein, glucose, fructose and sucrose in potato tubers (skin, flesh and whole tubers with skin), at harvest and after 5 months of storage. The experimental materials included tubers of five edible potato cultivars: Irga, Satina, Valfi, Blaue St. Galler and HB Red. During the growing season, potato plants were treated with the following biostimulants: Asahi SL, Bio-Algeen S-90, Kelpak SL and Trifender WP. Control plants were not treated with biostimulants. The total protein content of tubers was determined by the Kjeldahl method. Simple sugars and sucrose were determined by high-performance liquid chromatography. At harvest, total protein concentration was significantly higher in purple- and red-fleshed cultivars than in cream- and yellow-fleshed cultivars. An analysis of tuber parts revealed that flesh had the highest protein content. The total protein content of tubers increased during storage. Biostimulants had no significant effect on total protein concentration in tubers at harvest or after storage. The content of simple sugars and sucrose was higher in the skin, flesh and whole tubers of purple- and red-fleshed cultivars, than in cream- and yellow-fleshed cultivars. Potato tubers with colored flesh accumulated the highest amounts of total sugars. Biostimulants, in particular Bio-Algeen S-90 and Kelpak SL, contributed to the accumulation of monosaccharides and the disaccharide in potato tubers, and, in consequence, total sugars. Their concentrations in potato tubers increased during storage

Wpływ przewlekłego leczenia statyną na podatność tętnic w samoistnym nadciśnieniu tętniczym

Wstęp: Wyniki zakończonych niedawno dużych badań klinicznych wykazały zmniejszenie śmiertelności z przyczyn sercowo-naczyniowych u pacjentów z nadciśnieniem tętniczym otrzymujących statyny. W przebiegu nadciśnienia tętniczego dochodzi do postępującego sztywnienia ścian dużych tętnic, które przyspiesza powstawanie powikłań sercowych i mózgowych. Korzystny wpływ statyn na podatność tętnic mógłby więc stanowić wytłumaczenie obserwowanej po zastosowaniu tych leków poprawy rokowania u chorych z nadciśnieniem tętniczym. Celem pracy była ocena wpływu 6-miesięcznego leczenia simwastatyną na podatność tętnic w samoistnym nadciśnieniu tętniczym. Materiał i metody: Badana grupa obejmowała 52 pacjentów (37 mężczyzn i 15 kobiet) z pierwotnym nadciśnieniem tętniczym i wartościami stężenia cholesterolu mieszczącymi się w górnej granicy normy. Pacjentów podzielono w sposób losowy na dwie grupy. Do leków obniżających ciśnienie tętnicze w grupie 1 dodano simwastatynę (20 mg/d.), zaś w grupie 2 - placebo. Prędkość fali tętna (PWV) mierzono za pomocą aparatu COMPLIOR na początku i na końcu (po 6 miesiącach leczenia) badania. Wyniki: Obie grupy nie różniły się istotnie pod względem wartości ciśnienia tętniczego mierzonego na wstępie badania i po 6 miesiącach. U chorych leczonych simwastatyną wartości PWV obniżyły się po 6-miesięcznej terapii z 13,21 &plusmn; 1,83 m/s do 9,18 &plusmn; 0,59 m/s (p < 0,01). Natomiast w grupie otrzymującej placebo zanotowano nieistotną statystycznie tendencję do zmniejszenia PWV (12,98 &plusmn; 1,61 m/s na wstępie vs. 11,84 &plusmn; 1,19 m/s po 6 miesiącach). Wystąpiła niewielka, lecz istotna statystycznie dodatnia korelacja pomiędzy zmniejszeniem wartości PWV a obniżeniem stężenia cholesterolu frakcji LDL w surowicy (r = 0,31; p < 0,05). Wniosek: Sześciomiesięczna terapia simwastatyną spowodowała poprawę podatności dużych tętnic u pacjentów z nadciśnieniem tętniczym i granicznym stężeniem cholesterolu. (Folia Cardiol. 2004; 11: 929&#8211;937