Cartas enviadas por Aita Donostia (José Gonzalo Zulaika Arregi) a Justo Garate entre 1935 y 1953

5 cartas (manuscritas y mecanografiadas) ; 215x160mm. Ubicación: Caja 1 - Carpeta 12

Cartas enviadas por Violet Alford a Justo Garate en 1935

2 cartas (manuscritas) ; entre 192x199mm y 202x254mm. Ubicación: Caja 1 - Carpeta 21

Cartas enviadas por Telesforo de Aranzadi a Justo Garate entre 1935 y 1939

6 cartas y 3 tarjetas (mecanografiadas y manuscritas) ; entre 225x165mm y 140x90mm. Ubicación: Caja 1 - Carpeta 40

Cartas enviadas por Pío Baroja a Justo Garate entre 1931 y 1935

8 cartas (manuscritas) ; entre 320x210mm y 155x205mm y una tarjeta postal de 145x95mm

Reproducción de una Cédula de Citación remitida a D. Juan Manuel Epalza por el Juzgado de Instrucción Nº 2.

Fecha: 15-3-1935 (>1970 reproducción) / Unidad de instalación: Carpeta 25 - Expediente 23-2 / Nº de pág.: 1 (mecanografiada)

Ab initio study of anharmonicity in high pressure Cmca-4 metallic hydrogen

Hydrogen is the only atom for which the Schr odinger equation is solvable. Consisting only of a proton and an electron, hydrogen is the lightest element and, nevertheless, is far from being simple. Under ambient conditions, it forms diatomic molecules H2 in gas phase, but di erent temperature and pressures lead to a complex phase diagram, which is not completely known yet. Solid hydrogen was rst documented in 1899 [1] and was found to be isolating. At higher pressures, however, hydrogen can be metallized. In 1935 Wigner and Huntington predicted that the metallization pressure would be 25 GPa [2], where molecules would disociate to form a monoatomic metal, as alkali metals that lie below hydrogen in the periodic table. The prediction of the metallization pressure turned out to be wrong: metallic hydrogen has not been found yet, even under a pressure as high as 320 GPa. Nevertheless, extrapolations based on optical measurements suggest that a metallic phase may be attained at 450 GPa [3]. The interest of material scientist in metallic hydrogen can be attributed, at least to a great extent, to Ashcroft, who in 1968 suggested that such a system could be a hightemperature superconductor [4]. The temperature at which this material would exhibit a transition from a superconducting to a non-superconducting state (Tc) was estimated to be around room temperature. The implications of such a statement are very interesting in the eld of astrophysics: in planets that contain a big quantity of hydrogen and whose temperature is below Tc, superconducting hydrogen may be found, specially at the center, where the gravitational pressure is high. This might be the case of Jupiter, whose proportion of hydrogen is about 90%. There are also speculations suggesting that the high magnetic eld of Jupiter is due to persistent currents related to the superconducting phase [5]. Metallization and superconductivity of hydrogen has puzzled scientists for decades, and the community is trying to answer several questions. For instance, what is the structure of hydrogen at very high pressures? Or a more general one: what is the maximum Tc a phonon-mediated superconductor can have [6]? A great experimental e ort has been carried out pursuing metallic hydrogen and trying to answer the questions above; however, the characterization of solid phases of hydrogen is a hard task. Achieving the high pressures needed to get the sought phases requires advanced technologies. Diamond anvil cells (DAC) are commonly used devices. These devices consist of two diamonds with a tip of small area; for this reason, when a force is applied, the pressure exerted is very big. This pressure is uniaxial, but it can be turned into hydrostatic pressure using transmitting media. Nowadays, this method makes it possible to reach pressures higher than 300 GPa, but even at this pressure hydrogen does not show metallic properties. A recently developed technique that is an improvement of DAC can reach pressures as high as 600 GPa [7], so it is a promising step forward in high pressure physics. Another drawback is that the electronic density of the structures is so low that X-ray di raction patterns have low resolution. For these reasons, ab initio studies are an important source of knowledge in this eld, within their limitations. When treating hydrogen, there are many subtleties in the calculations: as the atoms are so light, the ions forming the crystalline lattice have signi cant displacements even when temperatures are very low, and even at T=0 K, due to Heisenberg's uncertainty principle. Thus, the energy corresponding to this zero-point (ZP) motion is signi cant and has to be included in an accurate determination of the most stable phase. This has been done including ZP vibrational energies within the harmonic approximation for a range of pressures and at T=0 K, giving rise to a series of structures that are stable in their respective pressure ranges [8]. Very recently, a treatment of the phases of hydrogen that includes anharmonicity in ZP energies has suggested that relative stability of the phases may change with respect to the calculations within the harmonic approximation [9]. Many of the proposed structures for solid hydrogen have been investigated. Particularly, the Cmca-4 structure, which was found to be the stable one from 385-490 GPa [8], is metallic. Calculations for this structure, within the harmonic approximation for the ionic motion, predict a Tc up to 242 K at 450 GPa [10]. Nonetheless, due to the big ionic displacements, the harmonic approximation may not su ce to describe correctly the system. The aim of this work is to apply a recently developed method to treat anharmonicity, the stochastic self-consistent harmonic approximation (SSCHA) [11], to Cmca-4 metallic hydrogen. This way, we will be able to study the e ects of anharmonicity in the phonon spectrum and to try to understand the changes it may provoque in the value of Tc. The work is structured as follows. First we present the theoretical basis of the calculations: Density Functional Theory (DFT) for the electronic calculations, phonons in the harmonic approximation and the SSCHA. Then we apply these methods to Cmca-4 hydrogen and we discuss the results obtained. In the last chapter we draw some conclusions and propose possible future work.

II Materialen Zientzia eta Teknologia Kongresua. Donostian, 2014 uztailak 3, 4

Egurra, sua; zura, mahaia; larrua, abarka; artila, galtzerdia; burnia, ardatza; altzairua, iltzea; buztina, teila; porlana, pareta; galipota, kaminoa… Materialak, tresnak. Zenbat aldiz aipatuak Euskal Herriko eguneroko berbeta, hizketa eta solasaldi arruntetan! Harria, herria, zioen Aresti poetak ere. Teknologiaren alorrari dagokionean, materialen gaia gehienbat metalurgiarekin lotu izan zen mundu osoan eta batik bat gure herrian. XX. mendearen hasieran garapen industrialak egundoko bultzada izan zuen, bereziki automobilgintzaren eta hegazkingintzaren hedapenarekin. Halaber, elektrizitatea arras zabaldu zelarik, etxetresnen kontzeptua bera ere aldatu egin zen. Horrela, tresna eta baliabide berriek gizartearen ohituren eta izaera beraren aldaketa sakonak erakarri zituzten. Baina, hori guztia material berriak sortu eta garatzeari zor zitzaion: polimeroak, metal eta zeramika berriak, estaldura sintetikoak, etab. ezinbestekoak bilakatu ziren. Orduan ikusi zen materialek arlo berezi bat merezi zutela zientziaren eremuan. Eta horrela, premiak eraginda, Fisika eta Kimika oinarrizko zientzietatik abiatua eta ingeniaritzaren gorpuzkera sendoaz hornituta, Materialen Zientzia sortu zen. Materialen Zientzia eta Teknologia euskaraz, beranduago etorriko zen. Askoz lehenagokoak dira “Pisia” eta “Kimia”, 1935 inguran Jauregi apaiz karmeldar aitzindariak idatzitako liburuak. Eta gero, iluntasunean bidexka ia ezinezkoak jorratuz, Elhuyar Taldea 1972an, Udako Euskal Unibertsitatea 1973an eta UZEI 1977an sortu ziren; euskara irakaskuntzara, unibertsitatera eta zientziara jalgi zedin. Hurrengo urtetan emaitzak gauzatzen hasiak ziren, bai eta Materialen Zientzia eta Teknologiaren arlo berrian ere. Izan ere, mugarria da, besteen artean, Nafarroako Unibertsitateko Donostiako Goi Mailako Injineru Eskolan 1979an Jon Nazabalek aurkeztu zuen “Zenbait mekanizapen errazeko altzairuren berotako erresistentzia mekanikoa eta duktibilitatea” doktoretzatesia. 1991ko uztailean, Udako Euskal Unibertsitateak “Materialen ezagutza teknika ezberdinen bitartez” topaketa antolatu zuen Iruñean, bertan 30en bat zientzialari euskaldun bildu ginelarik. Gaur egun, Euskal Herrian baditugu hainbat ingeniari, fisikari, kimikari eta biologo euskaldun, Materialen Zientzia eta Teknologia garatzen ari direnak, bai unibertsitate, bai zentro teknologiko eta enpresetan. Pertsona horien interesak, ikuspegiak eta lorpenak euskaraz azaltzeko antolatu zen 2012an Arrasaten Materialen Zientzia eta Teknologia I kongresua, ehunen bat pertsona bilduz. Orain dela bi urte hartutako konpromisoari helduz, eta harian haritik jarraituz, aurten Materialen Zientzia eta Teknologia II kongresua UPV/EHUko Polymat institutuak antolatu du. Aldez aurretik, mila esker dagoeneko parte hartzeko izena eman duten guztiei eta gure esker onenak erakunde laguntzaileei: Euskal Herriko Unibertsitatea, Kutxa, CicNanogune eta Elhuyar. Zientziak eta euskarak elkartzen gaituzte. Eta bietan badago elkartze gune bat: kinka larrian daudela beti. Ez baitago zientziarik zientzialariaren zalantzarik gabe, ez eta euskara euskaldun bakoitzaren nahi pertsonalik barik. Antxon Santamaria, Batzorde Antolatzailearen izenean