Diction is defined relating to four parts: (1) vocabulary, (2) author style and narrator tone, (3) abstraction, (4) formality.
(1) Vocabulary: Author choice among various options. For instance, to say a tree is in the setting, options are mulberry, deciduous, evergreen, abode of woodland nymph, etc. Each vocabulary selection establishes the imagery, mood, characterization.
(2) Style and Tone: Style refers to author, tone to narrator. Author style relates to complexity or simplicity of writing. Tone sets reader reaction and interaction with the topics and characters. For example, a satirical tone puts distance between reader and characters, while a sympathetic tone invites involvement between them.
(3) Abstraction: Diction can be concrete or abstract with levels in between. Abstraction is created by adjectives, verbs, and imagery that are related to either (1) the five senses or to (2) abstract ideas and actions. For example, concrete adjectives describe something as acrid, sharp, cool, etc, while abstract adjectives describe as unpleasant, painful, inviting. Concrete verbs are walked, jump, stood, etc, while abstract verbs are went, elevate, rose, etc.
(4) Formality: Classed as high or low, also called formal or informal. High, or formal, diction relates to the broad vocabulary choices and consists of sophisticated word and syntax choices or, at least, educated word and syntax choices ("short and simple" is the prevailing educated stylistic preference). Low, or informal, diction relates to vocabulary that consists of dialect, colloquial, conversational, and slang words and syntax choices.
Apply this to Raskolnikov.
He had successfully avoided meeting his landlady on the staircase. His garret was under the roof of a high, five-storied house and was more like a cupboard than a room. ... each time he passed, the young man had a sick, frightened feeling, which made him scowl and feel ashamed. He was hopelessly in debt to his landlady, and was afraid of meeting her.
This excerpt reveals a varied vocabulary: scowl, garret. Author style is complex: metaphor in the simile "like a cupboard"; subjugated and coordinated sentences: "The landlady who provided him with garret, dinners, and attendance, lived on the floor below, and every time ...." These sentences give information while establishing relationship between parts. Narrator tone is sympathetic, pitying (in a good sense), and worried. Raskolnikov's character will be developed in accord with this tone: this is how the reader will respond to him no matter what he does. There is a combination of abstract and concrete, though the greatest weight is on the concrete: abstract: successful, avoid, obliged, hopeless; concrete: five-storied, meet, pass, sick, frightened, feeling, shame, afraid. The narration and dialogue are high, formal diction. Even those who speak in dialect speak in a formal way: "'Step in, my good sir.'"
Since concrete and formal diction govern the narrative, it is easy to track Raskolnikov's developing character. We are told that in the beginning he is frightened and overwhelmed by feeling shame because of woeful debt. But as to resignation, there is no sign of it in his characterization, though there is sign of an emotional and psychological breakdown:
He was crushed by poverty, ... anxieties of his position had of late ceased to weigh upon him. He had given up attending to matters of ... importance; he lost all interest .... Nothing ... had a real terror for him.