Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
ABSTRAK
Sifat transportasi elektron di molekul DNA poly dA -poly dT telah dipelajari. Kami menggunakan dua model DNA yang berbeda, yang direpresentasikan secara matematis dengan model ikatan kuat Hamiltonian dan teori Slater-Koster. Panjang molekul DNA yang digunakan 32 pasangan basa. Kedua ujung rantai molekul dikoneksikan dengan elektroda. Sifat transportasi elektron dipelajari dari probabilitas transmisi dan karakteristik I-V. Probabilitas transmisi dihitung dengan metode transfer matriks dan matriks hamburan. Formula Landauer Buttiker digunakan untuk menghitung karakteristik I-V. Selanjutnya, sifat transportasi elektron dibandingkan di variasi temperatur, frekuensi getar gerak memutar dan energi gangguan lingkungan luar. Hasilnya menunjukan bahwa pada kedua model mengalami peningkatan probabilitas transmisi elektron dan arus seiring meningkatnya frekuensi getar gerak memutar rantai DNA. Namun saat temperatur ditingkatkan, probabilitas transmisi dan arusnya menurun dan tegangan ambang membesar di tiap variasi frekuensi getar. Kemudian ketika energi gangguan luar meningkat, probabilitas transmisi dan arus semakin kecil, demikian pula tegangan ambangnya. Nilai puncak-puncak probabilitas transmisi di model B lebih besar dari model A, namun kurva I-V model B dapat lebih besar atau lebih kecil. Peningkatan maupun penurunan transmisi dan arus di model A lebih besar ketika tidak ada gangguan backbone, tendensi terbalik ketika terdapat energi gangguan backbone.

---

ABSTRACT
The properties of electron transport in poly dA poly dT DNA molecules have been studied. We use two models of DNA which are represented mathematically by tight binding Hamiltonian model and Slater Koster theory. DNA molecules which are used have 32 base pairs long. Each end of DNA chain are connected to metallic electrodes. The properties of electron, are studied from transmission probability and I V characteristic curves. The transmission probabilities are calculated using transfer matrix and scattering matrix methods. The Landauer Buttiker formula is used in computing I V characteristics. The properties of transport electron are compared in variation of temperatures, frequencies of twisting motion and disorder energy due to environment. The results show that the transmission probability and current values increase as frequency of twisting motion increases in both of models. However, as temperature become higher, the transmission probability and current values decrease, but the treshold voltages increase for all frequency variations. Then, as disorder energy becomes higher, the transmission probability and current values decrease, and the threshold voltages decrease, too. Transmission probability values of model B are higher than model A, but the I V curve of model B can be higher and lower. Both of the enhancement or reduction of transmission and current in model A is higher for without backbone disorder energy condition, but the tendency reversed when in backbone disorder energy condition.

Abstrak :
Pendekatan Hamiltonian tight binding digunakan untuk mempelajari sifat transport muatan di molekul DNA. Sifat transport muatan ini dipelajari dengan menggunakan dua model DNA yaitu model DNA Aperiodik dan model DNA G4. Model DNA Aperiodik terdiri dari 32 pasangan basa ATGC yang tersusun secara acak dengan sequence GCTAGTACGTGACGTAGCTAGGATATGCCTGA. Pada model ini dilakukan perhitungan menggunakan metode transfer matriks dan metode hamburan untuk mendapatkan probabilitas transmisi serta menghitung karakteristik I-V berdasarkan formula Landauer Büttiker dengan memvariasikan nilai kopling 𝛼 interstrand. Peningkatan nilai kopling 𝛼 interstrand memberikan dampak yang sangat baik terhadap transport muatan yaitu terjadinya peningkatan probabilitas transmisi dan karakteristik IV pada tegangan tinggi. Sedangkan, model DNA G4 terdiri dari 4 basa guanine yang tersusun membentuk struktur planar, g-quartet yang disusun secara bertumpuk. Pada model DNA ini dilakukan perhitungan panjang lokalisasi menggunakan metode transfer matriks dan perhitungan density of state (DOS) dan karakteristik I-V menggunakan pendekatan fungsi green di bawah pengaruh temperatur dan medan magnet. Temperatur menyebabkan terjadinya fluktuasi termal yang menurunkan panjang lokalisasi, density of state (DOS) dan karakteristik I-V di molekul DNA G4. Sedangkan, medan magnet menyebabkan terjadinya pergeseran fase keadaan elektron di jalur transport yang mempengaruhi panjang lokalisasi dan DOS yang berimbas pada peningkatan arus hingga di tegangan tinggi. ...... The tight binding Hamiltonian approach is used in studying charge transport properties DNA molecules. The charge transport properties are studied by using two DNA models, the Aperiodic DNA molecule and the G4 DNA molecule. The Aperiodic DNA model consist of 32 base pairs that ATGC arranged randomly with sequence GCTAGTACGTGACGT-AGCTAGGATATGCCTGA. In this model, transfer matrix method and scattering method are used in obtain transmission probability and calculating the I-V characteristic for various values of interstrand coupling α. The increase of α gives a very good impact on charge transport that is the increase of transmission probability and I-V characteristic at high voltages. G4 DNA model consists of planar structure of four guanine bases, g-quartet, which are stacked on top each other. In this DNA model, localization length is calculated using transfer matrix method and the density of state (DOS) as well as I-V characteristic are calculated using green function approach under the influence of temperature and magnetic field. The temperature causes thermal fluctuations that decreases the localization length, density of state (DOS) and I-V characteristics in G4 DNA molecule. Meanwhile, magnetic field causes a shift in electron wave phase along its travel path which is affecting the localization length and DOS which lead to current increament up to high voltage.