Andrea Dal Corso's publications (H-index=40)



Submitted for publication 2025

108. B. Thakur, X. Gong, and A. Dal Corso,
Thermodynamic properties of fcc lead: A scalar and fully relativistic first principle study,
submitted.

107. A. Dal Corso,
Elastic constants of hcp elements: a first-principles investigation,
submitted.


2025

106. X. Gong and A. Dal Corso,
An alternative GPU acceleration for a pseudopotential plane-waves density functional theory code with applications to metallic systems,
Comp. Phys. Comm. 308, 109439 (2025). [reprint.pdf]


2024

105. X. Gong and A. Dal Corso,
High temperature and pressure thermoelasticity of hcp metals from ab initio quasi-harmonic free energy calculations: the beryllium case,
Phys. Rev. B 110, 094109 (2024). [reprint.pdf]

104. X. Gong and A. Dal Corso,
Ab-initio quasi-harmonic thermoelasticity of molybdenum at high temperature and pressure,
Jour. Chem. Phys. 160, 244703 (2024). [reprint.pdf]

103. X. Gong and A. Dal Corso,
Pressure and temperature dependent ab-initio quasi-harmonic thermoelastic properties of tungsten,
Jour. of Phys.: Condens. Matter 36, 285702 (2024). [reprint.pdf]

102. B. Thakur, X. Gong, and A. Dal Corso,
Thermodynamic properties of Rhodium: A first principles study,
AIP Advances 14, 045229 (2024). [reprint.pdf]

101. B. Thakur, X. Gong, and A. Dal Corso,
Ab initio thermodynamic properties of Iridium: A high-pressure and high-temperature study,
Comp. Materials Science 234, 112797 (2024). [reprint.pdf]



2022

100. C. Malica and A. Dal Corso,
Finite-temperature atomic relaxations: Effect on the temperature-dependent C44 elastic constants of Si and BAs,
Jour. Chem. Phys. 156, 194111 (2022). [reprint.pdf]


2021

99. C. Malica and A. Dal Corso,
Quasi-harmonic thermoelasticity of palladium, platinum, copper, and gold from first principles,
J. of Phys.: Condens. Matter 33, 475901 (2021). [reprint.pdf]


2020

98. A. Urru and A. Dal Corso,
Lattice dynamics effects on the magnetocrystalline anisotropy energy: application to MnBi,
Phys. Rev. B 102, 115126 (2020). [reprint.pdf]

97. O. Motornyi, N. Vast, I. Timrov, O. Baseggio, S. Baroni, and A. Dal Corso,
Electron energy loss spectroscopy of bulk gold with ultrasoft pseudopotentials and the Liouville-Lanczos method,
Phys. Rev. B 102, 035156 (2020). [reprint.pdf]

96. C. Malica and A. Dal Corso,
Temperature dependent elastic constants and thermodynamic properties of BAs: an ab-initio investigation,
Jour. of Applied Phys. 127, 245103 (2020). [reprint.pdf]

95. C. Malica and A. Dal Corso,
Quasi-harmonic temperature dependent elastic constants: Applications to Silicon, Aluminum, and Silver,
J. of Phys.: Condens. Matter 32, 315902 (2020). [reprint.pdf]


2019

94. A. Urru and A. Dal Corso,
Density functional perturbation theory for lattice dynamics with fully relativistic ultrasoft pseudopotentials: The magnetic case,
Phys. Rev. B 100, 045115 (2019). [reprint.pdf]

93. C. Malica and A. Dal Corso,
Temperature dependent atomic B-factor: an ab-initio calculation,
Acta Cryst. A 75, 624 (2019). [reprint.pdf]

92. A. Urru and A. Dal Corso,
Spin-polarized electronic surface states of Re(0001): an ab-initio investigation,
Surf. Sci. 686, 22 (2019). [reprint.pdf]


2018

91. O. Motornyi, M. Raynaud, A. Dal Corso, and N. Vast,
Simulation of electron energy loss spectra with the turboEELS and thermo_pw codes,
J. Phys.: Conf. Ser. 1136, 012008 (2018). [reprint.pdf]

90. A. Urru and A. Dal Corso,
Clean Os(0001) electronic surface states: a first-principle fully relativistic investigation,
Surf. Sci. 671, 17 (2018). [reprint.pdf], [arXiv:1801.09267]


2017

89. [4486] P. Giannozzi et. al.,
Advanced capabilities for materials modelling with Quantum ESPRESSO,
J. of Phys.: Condens. Matter 29, 465901 (2017). [reprint.pdf]

88. M. Palumbo and A. Dal Corso,
Lattice dynamics and thermophysical properties of h.c.p. Os and Ru from the quasi-harmonic approximation,
J. of Phys.: Condens. Matter 29, 395401 (2017). [reprint.pdf]

87. M. Palumbo and A. Dal Corso,
Lattice dynamics and thermophysical properties of h.c.p. Re and Tc from the quasi-harmonic approximation,
Phys. Status Solidi B: Basic Solid State Physics, 254, 1700101 (2017). [reprint pdf]


2016

86. [952] K. Lejaeghere, et. al.
Reproducibility in density-functional theory calculations of solids,
Science, 351, aad3000 (2016). [reprint pdf]

85. [116] A. Dal Corso,
Elastic constants of Beryllium: a first-principles investigation,
J. Phys.: Condens. Matter 28, 075401 (2016). [reprint pdf]


2015

84. A. Dal Corso,
Clean Ir(111) and Pt(111) electronic surface states: a first-principle fully relativistic investigation,
Surf. Sci. 637-638, 106 (2015). [reprint pdf]


2014

83. [1036] A. Dal Corso,
Pseudopotentials periodic table: from H to Pu,
Comp. Materials Science 95, 337 (2014). [reprint pdf]

82. M. Palumbo, S.G. Fries, A. Dal Corso, F. Kormann, T. Hickel, and J. Neugebauer,
Reliability evaluation of thermophysical properties from first-principles calculations,
J. Phys.: Condens. Matter 26, 335401 (2014). [reprint pdf]


2013

81. [43] A. Dal Corso,
Ab-initio phonon dispersions of transition and noble metals: effects of the exchange and correlation functional,
J. Phys.: Condens. Matter 25, 145401 (2013). [reprint pdf]

80. G. Sclauzero and A. Dal Corso,
Efficient DFT+U calculations of ballistic electron transport: Application to Au monatomic chains with a CO impurity,
Phys. Rev. B 87, 085108 (2013). [reprint pdf]


2012

79. A. Dal Corso,
Projector augmented-wave method with spin-orbit coupling: applications to simple solids and zincblende-type semiconductors,
Phys. Rev. B 86, 085135 (2012). [reprint pdf]

78. G. Sclauzero, A. Dal Corso, and A. Smogunov,
Effect of stretching on the ballistic conductance of Au nanocontacts in presence of CO: a density functional study,
Phys. Rev. B 85, 165412 (2012). [reprint pdf]

77. G. Sclauzero, A. Dal Corso, and A. Smogunov,
Interaction of CO with an Au monatomic chain at different strains: electronic structure and ballistic transport,
Phys. Rev. B 85, 165411 (2012). [reprint pdf]

76. A. Dal Corso and L. Paulatto,
Density functional perturbation theory within the projector augmented-wave method: a few benchmarks for molecules and solids,
AIP Conf. Proc. 1504, 932 (2012). [reprint pdf]


2011

75. [51] A. A. Adllan and A. Dal Corso,
Ultrasoft pseudopotentials and projector augmented-wave data sets: application to diatomic molecules,
J. Phys.: Condens. Matter 23, 425501 (2011). [reprint pdf]

74. S. Sorella, M. Casula, L. Spanu, and A. Dal Corso,
Ab-initio calculations for the β-tin diamond transition in Silicon: comparing theories with experiments,
Phys. Rev. B 83, 075119 (2011). [reprint pdf]


2010

73. [66] A. Dal Corso,
Projector augmented-wave method: application to relativistic spin-density functional theory,
Phys. Rev. B 82, 075116 (2010). [reprint pdf]

72. A. Dal Corso,
Density functional perturbation theory within the projector augmented-wave method,
Phys. Rev. B 81, 075123 (2010). [reprint pdf]

71. P. Gava, A. Dal Corso, A. Smogunov, and E. Tosatti,
Magnetism-induced ballistic conductance changes in Palladium nanocontacts,
Eur. Phys. J. B 75, 57 (2010). [reprint pdf]


2009

70. [20474] P. Giannozzi, et al.,
Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials,
J. Phys.: Condens. Matter 21, 395502 (2009). [reprint pdf]

69. R. di Meo, A. Dal Corso, P. Giannozzi, and S. Cozzini,
Calculation of phonon dispersions on the GRID using Quantum ESPRESSO,
ICTP lecture notes 24, 163 (2009). [reprint pdf]


2008

68. A. Dal Corso,
Ab-initio phonon dispersions of face centered cubic Pb: effects of spin-orbit coupling,
J. Phys.: Condens. Matter 20, 445202 (2008). [reprint pdf]

67. R. Mazzarello, A. Dal Corso, and E. Tosatti,
Spin-orbit modifications and splittings of deep surface states on clean Au(111),
Surf. Sci. 602, 893 (2008). [reprint pdf]

66. G. Sclauzero, A. Dal Corso, A. Smogunov, and E. Tosatti,
Interaction of a CO molecule with a Pt monatomic wire: electronic structure and ballistic conductance,
Phys. Rev. B 78, 085421 (2008). [reprint pdf]

65. [40] A. Smogunov, A. Dal Corso, and E. Tosatti,
Magnetic phenomena, spin-orbit effects, and Landauer conductance in Pt nanowire contacts: Density-functional theory calculations,
Phys. Rev. B 78, 014423 (2008). [reprint pdf]

64. [84] A. Smogunov, A. Dal Corso, A. Delin, R. Weht, and E. Tosatti,
Colossal magnetic anisotropy of monatomic free and deposited platinum nanowires,
Nature Nanotechnology 3, 22 (2008). [reprint pdf]

63. G. Sclauzero, A. Dal Corso, A. Smogunov, and E. Tosatti,
Interaction of a CO molecule with a Pt monatomic chain: the top geometry,
AIP Conf. Proc. 1018, 201 (2008). [reprint pdf]

62. Y. Miura, R. Mazzarello, A. Dal Corso, A. Smogunov, and E. Tosatti,
Monatomic Au wire with a magnetic Ni impurity: electronic structure and ballistic conductance,
Phys. Rev. B 78, 205412 (2008). [reprint pdf]

61. N. Stojic, A. Dal Corso, B. Zhou, and S. Baroni,
Ab-initio simulation of photoemission spectroscopy in solids: plane-waves pseudopotential approach with applications to normal emission spectra of Cu(001) and Cu(111),
Phys. Rev. B 77, 195116 (2008). [reprint pdf]


2007

60. A. Dal Corso,
Density functional perturbation theory for lattice dynamics with fully relativistic ultrasoft pseudopotentials: application to fcc-Pt and fcc-Au,
Phys. Rev. B 76, 054308 (2007). [reprint pdf]

59. A. Aravindh, et al.,
Six C1-x O2 alloys: a possible route to stabilize carbon-based silica-like solids?
Solid State Comm. 144, 273 (2007). [reprint pdf]


2006

58. A. Dal Corso, A. Smogunov, and E. Tosatti,
Ab-initio ballistic conductance with spin-orbit coupling: application to monatomic wires,
Phys. Rev. B 74, 045429 (2006). [reprint pdf]

57. A. Smogunov, A. Dal Corso, and E. Tosatti,
Ballistic conductance and magnetism in short tip-suspended Ni nanowires,
Phys. Rev. B 73, 075418 (2006). [reprint pdf]

56. N. Bonini, A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
Structure and dynamics of the missing-row reconstruction on O/Cu(001) and O/Ag(001),
Surf. Sci. 600, 5074 (2006). [reprint pdf]

55. A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
DFT study of a weakly π-bonded C2H4 on oxygen-covered Ag(100),
J. Phys. Chem. B 110, 367 (2006). [reprint pdf]


2005

54. [227] A. Dal Corso and A. Mosca Conte,
Spin-orbit coupling with ultrasoft pseudopotentials: application to Au and Pt,
Phys. Rev. B 71, 115106 (2005). [reprint pdf]

53. C. Grazioli, D. Alfè, S.R. Krishnakumar, S.S. Gupta, M. Veronese, S. Turchini, N. Bonini, A. Dal Corso, D.D. Sarma, S. Baroni, and C. Carbone,
Spin-flop ordering from frustrated ferro- and antiferromagnetic interactions: a combined theoretical and experimental study of a Mn/Fe(100) monolayer,
Phys. Rev. Lett. 95, 117201 (2005). [reprint pdf]

52. N. Bonini, A. Dal Corso, A. Kokalj, S. de Gironcoli, and S. Baroni,
On-surface and sub-surface oxygen adsorption on Ag(210): vibrational properties,
Surf. Sci. 587, 50 (2005). [reprint pdf]


2004

51. [170] A. Smogunov, A. Dal Corso, and E. Tosatti,
Ballistic conductance of magnetic Co and Ni nanowires with ultrasoft pseudo-potentials,
Phys. Rev. B 70, 045417 (2004). [reprint pdf]

50. A. Smogunov, A. Dal Corso, and E. Tosatti,
Ballistic conductance of Ni nanowire with a magnetization reversal,
Surf. Sci. 566-568, 390 (2004). [reprint pdf]

49. J. Tobik and A. Dal Corso,
Electric fields with ultrasoft pseudo-potentials: applications to benzene and anthracene,
Jour. of Chem. Phys. 120, 9934 (2004). [preprint pdf]

48. N. Bonini, A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
Structure and dynamics of Oxygen adsorbed on Ag(100) vicinal surfaces,
Phys. Rev. B 69, 195401 (2004). [reprint pdf]

47. N. Bonini, A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
On-surface and subsurface adsorption of oxygen on stepped Ag(210) and Ag(410) surfaces,
Surf. Sci. 566-568, 1107 (2004). [reprint pdf]

46. A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
Adsorption of ethylene on stepped Ag(n10) surfaces,
Surf. Sci. 566-568, 1018 (2004). [reprint pdf]

45. J. Tobik, A. Dal Corso, S. Scandolo, and E. Tosatti,
Organic molecular crystals in electric fields,
Surf. Sci. 566-568, 644 (2004). [reprint pdf]


2003

44. A. Smogunov, A. Dal Corso, and E. Tosatti,
Complex band structure with ultrasoft pseudopotentials: fcc Ni and Ni nanowire,
Surf. Sci. 532-535, 549 (2003). [reprint pdf]

43. [41] F. Picaud, A. Smogunov, A. Dal Corso, and E. Tosatti,
Complex band structures and decay length in polyethylene chains,
J. Phys.: Condens. Matter 15, 3731 (2003). [reprint pdf]

42. [171] C. Bungaro, K.M. Rabe, and A. Dal Corso,
First-principles study of lattice instabilities in the ferromagnetic martensite Ni2MnGa,
Phys. Rev. B 68, 134104 (2003). [reprint pdf]

41. [76] M. Cococcioni, A. Dal Corso, and S. de Gironcoli,
Structural, electronic and magnetic properties of Fe2SiO4, Fayalite: Comparison of LDA and GGA results,
Phys. Rev. B 67, 094106 (2003). [reprint pdf]

40. D. Loffreda, A. Dal Corso, S. Baroni, L. Savio, L. Vattuone, and M. Rocca,
Oxygen vibrations in O-Ag(001),
Surf. Sci. 530, 26 (2003). [reprint pdf]

39. A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
Co-adsorption of ethylene and oxygen on the Ag(001) surface,
Surf. Sci. 532-535, 191 (2003). [reprint pdf]

38. F. Picaud, A. Dal Corso, and E. Tosatti,
Phonons softening in tip-stretched monatomic nanowires,
Surf. Sci. 532-535, 544 (2003). [reprint pdf]


2002

37. [43] A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
The interaction of ethylene with perfect and defective Ag(001) surfaces,
Jour. Phys. Chem. B 106, 9839 (2002). [reprint pdf]

36. M. Luders, A. Bordoni, N. Manini, A. Dal Corso, M. Fabrizio, and E. Tosatti,
Coulomb couplings in positively charged fullerene,
Philos. Mag. B 82, 1611 (2002).

35. N. Manini, G. Santoro, A. Dal Corso, E. Tosatti,
Sensitivity of the Mott transition to noncubic splitting of the orbital degeneracy: Application to NH3K3C60,
Phys. Rev. B 66, 115107 (2002). [reprint pdf]

34. A. Kokalj, A. Dal Corso, S. de Gironcoli, and S. Baroni,
Adsorption of ethylene on the Ag(001) surface,
Surf. Sci. 507-510, 62 (2002). [reprint pdf]

33. A. Smogunov, A. Dal Corso, and E. Tosatti,
Selective d-state conduction blocking in nickel nanocontacts,
Surf. Sci. 507-510, 609 (2002). [reprint pdf]

32. [47] G. Cipriani, D. Loffreda, A. Dal Corso, S. de Gironcoli, and S. Baroni,
Adsorption of atomic oxygen on Ag(001): A study based on density-functional theory,
Surf. Sci. 501, 182 (2002). [reprint pdf]


2001

31. [6850] S. Baroni, S. de Gironcoli, A. Dal Corso, and P. Giannozzi,
Phonons and related crystal properties from density-functional perturbation theory,
Rev. Mod. Phys. 73, 515 (2001). [reprint pdf]

30. [71] A. Dal Corso,
Density-functional perturbation theory with ultrasoft pseudopotentials,
Phys. Rev. B 64, 235118 (2001). [reprint pdf]

29. [66] N. Manini, A. Dal Corso, M. Fabrizio, and E. Tosatti,
Electron--vibration coupling constants in positively charged fullerene,
Phil. Mag. B 73, 793 (2001).

28. L. Savio, L. Vattuone, M. Rocca, V. De Renzi, S. Gardonio, C. Mariani, U. del Pennino, G. Cipriani, A. Dal Corso, and S. Baroni,
Substrate reconstruction and electronic surface states: Ag(001),
Surf. Sci. 486, 65 (2001). [reprint pdf]

27. [156] P. Umari, A. Pasquarello, and A. Dal Corso,
Raman scattering intensities in α-quartz: A first-principles investigation,
Phys. Rev. B 63, 094305 (2001). [reprint pdf]

26. F. Favot, A. Dal Corso, and A. Baldereschi,
Ab-initio study of CO adsorption on Ni(110): Effects on surface magnetism at low coverage,
Phys. Rev. B 63, 115416 (2001). [reprint pdf]

25. [269] E. Tosatti, S. Prestipino, S. Koestlmeier, A. Dal Corso, and F. Di Tolla,
String tension and stability of magic tip-suspended nanowires
Science 291, 288 (2001). [reprint pdf]

24. F. Favot, A. Dal Corso, and A. Baldereschi,
CO adsorbed on Cu(001): A comparison between local density approximation and Perdew, Burke, and Ernzerhof generalized gradient approximation,
Jour. of Chem. Phys. 114, 483 (2001). [reprint pdf]


2000

23. F. Favot, A. Dal Corso, and A. Baldereschi,
Absorption geometry of benzene on Pd(110): Results of first-principles calculations,
Europh. Lett. 52, 698 (2000). [reprint pdf]

22. [45] F. Di Tolla, A. Dal Corso, J. A. Torres, and E. Tosatti,
Electronic properties of ultra-thin aluminum nanowires,
Surf. Sci. 454-456, 947 (2000).

21. F. Favot, A. Dal Corso, and A. Baldereschi,
Ab-initio study of the structure of Pd(110)-c(4x2)-benzene,
Surface Rev. and Lett. 6, 903 (1999). [reprint pdf]

20. [85] A. Dal Corso and S. de Gironcoli,
Ab-initio phonon dispersions of Fe and Ni,
Phys. Rev. B 62, 273 (2000). [reprint pdf]

19. M. Magagnini, P. Giannozzi, and A. Dal Corso,
Microscopic structure of the substitutional aluminum defect in α-quartz,
Phys. Rev. B. 61, 2621 (2000). [reprint pdf]


1999

18. [49] V. Musolino, A. Dal Corso, and A. Selloni,
Initial stages of growth of copper on MgO(100): A first principles study,
Phys. Rev. Lett. 83, 2761 (1999). [reprint pdf]

17. [104] F. Favot and A. Dal Corso,
Phonon dispersions: Performance of the generalized gradient approximation,
Phys. Rev. B. 60, 11427 (1999). [reprint pdf]

16. [264] R. Lazzari, N. Vast, J.M. Besson, S. Baroni, and A. Dal Corso,
Atomic structure and vibrational properties of icosahedral B4 C boron carbide,
Phys. Rev. Lett. 83 , 3230 (1999). [reprint pdf]

15. F. Mauri and A. Dal Corso,
Vibrational properties of tetrahedral amorphous carbon from first principles,
Appl. Phys. Lett. 75, 644 (1999). [reprint pdf]

14. [123] J.A. Torres, E. Tosatti, A. Dal Corso, F. Ercolessi, J. Kohanoff, F. Di Tolla, and J.M. Soler,
The puzzling stability of monatomic gold wires,
Surf. Sci. Lett. 426, L441 (1999). [reprint pdf]


1998

13. [82] C. Massobrio, A. Pasquarello, and A. Dal Corso,
Structural and electronic properties of small Cun clusters using generalized-gradient approximations within density functional theory,
Jour. of Chem. Phys. 109, 6626 (1998). [reprint pdf]

12. P. Fernandez, A. Dal Corso, and A. Baldereschi,
Ab initio study of the dielectric properties of silicon and gallium arsenide using polarized Wannier functions,
Phys. Rev. B (Rapid Communication) 58, R7480 (1998). [reprint pdf]


1997

11. P. Fernandez, A. Dal Corso, F. Mauri, and A. Baldereschi,
First-principle Wannier functions of silicon and gallium arsenide,
Phys. Rev. B (Rapid Communication) 55, 1909 (1997). [reprint pdf]

10. [67] A. Dal Corso, A. Pasquarello, and A. Baldereschi,
Density-functional perturbation theory for lattice dynamics with ultrasoft pseudopotentials,
Phys. Rev. B (Rapid Communication) 56, R11369 (1997). [reprint pdf]


1996

9. [101] A. Dal Corso, F. Mauri, and A. Rubio,
Density-functional theory of nonlinear optical susceptibility: Application to cubic semiconductors,
Phys. Rev. B 53, 15638 (1996). [reprint pdf]

8. [193] A. Dal Corso, A. Pasquarello, A. Baldereschi, and R. Car,
Generalized gradient approximations to density functional theory: A comparative study for atoms and solids,
Phys. Rev. B 53, 1180 (1996). [reprint pdf]


1994

7. [243] A. Dal Corso, M. Posternak, R. Resta and A. Baldereschi,
Ab-initio study of piezoelectricity and spontaneous polarization in ZnO,
Phys. Rev. B 50, 10715 (1994). [reprint pdf]

6. [57] A. Dal Corso and F. Mauri,
Wannier and Bloch orbital computation of nonlinear susceptibility,
Phys. Rev. B (Rapid Communication) 50, 5756 (1994). [reprint pdf]

5. [49] A. Dal Corso and R. Resta,
Density-functional theory of macroscopic stress: Gradient-corrected calculations for crystalline Se,
Phys. Rev. B 50, 4327 (1994). [reprint pdf]

4. [74] A. Dal Corso, S. Baroni, and R. Resta,
Density-functional theory of the dielectric constant: Gradient corrected calculation for silicon,
Phys. Rev. B 49, 5323 (1994). [reprint pdf]


1993

3. [55] A. Dal Corso, R. Resta, and S. Baroni,
Non linear piezoelectricity in CdTe,
Phys. Rev. B 47, 16252 (1993). [reprint pdf]

2. A. Dal Corso and E. Tosatti,
Face-dependent Hamaker constants and surface melting or non-melting of non-cubic crystals,
Phys. Rev. B 47, 9742 (1993). [reprint pdf]

1. [172] A. Dal Corso, S. Baroni, R. Resta, and S. de Gironcoli,
Ab-initio calculation of phonon dispersions in II-VI semiconductors,
Phys. Rev. B 47, 3588 (1993). [reprint pdf]


[≥ H] Most cited papers. Source ISI (Dec. 2023).
For information please contact
dalcorso .at. sissa.it