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Abstrak :
ABSTRAK
Kami mempelajari sifat transport muatan menggunakan molekul DNA aperiodik dan molekul DNA G4. Molekul DNA aperiodik mempelajari pengaruh nilai loncatan inter-strand pada karakteristik I-V. Molekul DNA G4 mempelajari pengaruh medan listrik dan medan magnet pada panjang lokalisasi, density of state DOS , dan karakteristik I-V. Sifat transport muatan dipelajari dengan menghitung probabilitas transmisi, karakteristik I-V, dan memberikan pengaruh medan listrik dan medan magnet. Pada molekul DNA aperiodik, dipelajari pengaruh nilai hopping inter-strand terhadap probabilitas transmisi dan karakteristik I-V. Probabilitas transmisi dihitung dengan metode transfer matriks, sedangkan karakteristik I-V dihitung dengan formula Launder-Buttiker. Pada molekul DNA G4, dipelajari pengaruh medan listrik dan medan magnet terhadap panjang lokalisasi, density of state DOS, dan karakteristik I-V. Panjang lokalisasi dihitung menggunakan metode transfer matriks, dan density of state DOS serta karakteristik I-V dihitung dengan metode fungsi Green.

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ABSTRACT
The charge transport of aperiodic DNA and G4 DNA molecule have been studied. On the aperiodic DNA molecule, the effect of the inter-strand hopping value on the I-V characteristic has been studied. The effect of the electric and magnetic field on the localization length, density of state (DOS), and I-V characteristics were studied G4 DNA molecule. Charge transport was studied by calculating the transmission probability, the I-V characteristic, by considering the effect of the electric and the magnetic field. In the aperiodic DNA molecule, we study the effect of hopping inter-strand on transmission probability and I-V characteristics. The transmission probability was calculated by the matrix transfer method, while the I-V characteristic was calculated by the Launder-Buttiker formula. In G4 DNA molecule, we studied the effect of the electric and magnetic field on the localization length, density of state (DOS), and I-V characteristic. Localization length was calculated using matrix transfer method, and density of state (DOS) and I-V characteristic was calculated by Green function method.

Abstrak :
ABSTRAK
Banyak faktor yang dapat mengubah struktur energi DNA, dan pada akhirnya, hal tersebut berpengaruh kepada transpor elektron pada molekul DNA. Studi yang dilakukan berfokus kepada pengaruh medan listrik pada properti transpor muatan dari molekul DNA poly(dA)-poly(dT). Model DNA pada studi ini memperbolehkan elektron untuk mengalir dari backbone ke backbone. Model hamiltonian tight-binding digunakan dengan melibatkan medan listrik dan temperatur. Medan listrik diatur sejajar dengan sumbu heliks DNA. Medan listrik dimodelkan dengan mengacu pada formula Miller-Abraham yang mengubah konstanta hopping antar-sites dalam DNA. Metode transfer-matrix dan ortonormalisasi Gram-Schmidt digunakan untuk menghitung panjang lokalisasi. Retarded Green Function digunakan untuk menghitung DOS. Hasil yang didapatkan menunjukkan bahwa ketika medan listrik meningkat, terjadi pelebaran celah pada panjang lokalisasi dan DOS. Sedangkan peningkatan suhu meningkatkan disorder pada sistem.

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ABSTRACT
There are many factors that can change the energy structure of DNA, and in the end it can affects electronic transport in DNA molecules. The study will focus on the influence of the electric field on the charge transport properties of the poly(dA)-poly (dT) DNA molecule. The DNA model in this study allows electrons to propagate from the backbone to backbone. The tight-binding Hamiltonian model is used by taking into account the electric field and temperature influence. The electric field is applied parallel to the helical axis of DNA. The electric field which change the hopping constant between sites in DNA will be modeled by using  the Miller-Abraham formula. The transfer-matrix method and Gram-Schmidt orthonormalisation method are used to calculate the length of localization. Retarded Green Function is used to calculate DOS. The results obtained show that when electric field increases, there will be widening of the gap at the localization length and DOS. While the increase in temperature will increase disorder in the system.

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.

Abstrak :
Sifat transpor muatan pada molekul DNA untai ganda dan DNA G4 telah dipelajari. Kami menggunakan dua model DNA yang direpresentasikan secara matematis dengan menggunakan model Hamiltonian tight binding. Model yang pertama adalah DNA untai ganda dengan panjang 32 pasangan basa yang disusun secara random. Transpor muatan untuk molekul DNA ini dipelajari dari probabilitas transmisi dan karakteristik I-V dengan memvariasikan hopping elektron inter-strand tegak lurus. Peningkatan hopping electron inter-strand tegak lurus menyebabkan probabilitas transmisi dan arus meningkat, tetapi saat temperaturnya dinaikkan probabilitas transmisi dan arus menurun. Model kedua adalah DNA G4, Sifat transpor muatan pada molekul ini dipelajari dari panjang lokalisasi dengan panjang 102 pasangan basa, density of states dan karakteristik I-V masing-masing dengan 32 tumpukan tetrad guanin, yang diberi pengaruh medan listrik dan temperatur, Probabilitas transmisi dan panjang lokalisasi dihitung menggunakan metode transfer matriks. Formula landauer Buttiker digunakan untuk menghitung karakteristik I-V. Metode fungsi green untuk menghitung probabilitas transmisi dan density of states. Hasil perhitungan medan listrik dan temperatur terhadap sifat transpor muatan yaitu menurunkan panjang lokalisasi, density of states, dan arus, saat meningkatnya medan listrik dan temperatur. ...... The charge transport property on double-stranded DNA and G4 DNA molecules has been studied. We use two DNA models that are mathematically represented using Hamiltonian tight binding models. The first model is double stranded DNA with length of 32 base pairs arranged randomly. The charge transport for this DNA molecule is studied from transmission probabilities and I-V characteristics by varying of electron hopping in perpendicular inter-strand. Increased of electron hopping in perpendicular inter-strand causes the transmission and current probabilities to increase, but when temperature is increased the transmission probabilities and current is decrease. The second model is DNA G4. The charge transport property in this molecule is studied from localization length with length of 102 base pairs, density of states and I-V characteristics with 32 stacks of guanine tetrads respectively that influenced of electric field and temperature. Transmission probability and localization length are calculated using matrix transfer method. The buttiker landauer formula is used to calculate the I-V characteristics. Green function method for calculating transmission probability and density of states. The result of electric field and temperature calculation on charge transport leads to decreasing localization length, density of states, and current, when increasing of electric field and temperature.